{"id":1193,"date":"2025-03-24T08:52:38","date_gmt":"2025-03-23T23:52:38","guid":{"rendered":"https:\/\/dexall.co.jp\/articles\/?p=1193"},"modified":"2025-03-24T08:52:38","modified_gmt":"2025-03-23T23:52:38","slug":"%e3%80%90%e4%bf%9d%e5%ad%98%e7%89%88%e3%80%91java-persistence-api%e5%ae%8c%e5%85%a8%e3%82%ac%e3%82%a4%e3%83%89%ef%bc%9a%e5%ae%9f%e8%a3%85%e6%89%8b%e9%a0%86%e3%81%a87%e3%81%a4%e3%81%ae%e9%87%8d","status":"publish","type":"post","link":"https:\/\/dexall.co.jp\/articles\/?p=1193","title":{"rendered":"\u3010\u4fdd\u5b58\u7248\u3011Java Persistence API\u5b8c\u5168\u30ac\u30a4\u30c9\uff1a\u5b9f\u88c5\u624b\u9806\u30687\u3064\u306e\u91cd\u8981\u30dd\u30a4\u30f3\u30c8"},"content":{"rendered":"\n<h1 class=\"wp-block-heading\" id=\"i-0\">JPA\u3068\u306f\uff1f\u57fa\u790e\u304b\u3089\u7406\u89e3\u3059\u308b\u6c38\u7d9a\u5316\u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af<\/h1>\n\n\n\n<div class=\"toc\"><br \/>\n<b>Warning<\/b>:  Undefined array key \"is_admin\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>116<\/b><br \/>\n<br \/>\n<b>Warning<\/b>:  Undefined array key \"is_category_top\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>121<\/b><br \/>\n<br \/>\n<b>Warning<\/b>:  Undefined array key \"is_top\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>128<\/b><br \/>\n    <div id=\"toc_container\" class=\"sgb-toc--bullets js-smooth-scroll\" data-dialog-title=\"\u76ee\u6b21\">\n      <p class=\"toc_title\">\u76ee\u6b21 <\/p>\n      <ul class=\"toc_list\">  <li class=\"first\">    <a href=\"#i-0\">JPA\u3068\u306f\uff1f\u57fa\u790e\u304b\u3089\u7406\u89e3\u3059\u308b\u6c38\u7d9a\u5316\u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-1\">JPA\u304c\u89e3\u6c7a\u3059\u308b3\u3064\u306e\u958b\u767a\u8ab2\u984c<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-5\">\u5f93\u6765\u306eJDBC\u3068\u306e\u6c7a\u5b9a\u7684\u306a\u9055\u3044<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-9\">JPA \u306e\u57fa\u672c\u6a5f\u80fd\u3068\u5b9f\u88c5\u624b\u9806<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-10\">\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u30af\u30e9\u30b9\u306e\u4f5c\u6210\u65b9\u6cd5\u3068\u91cd\u8981\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3<\/a>      <\/li>      <li>        <a href=\"#i-13\">EntityManager \u306e\u52b9\u679c\u7684\u306a\u4f7f\u3044\u65b9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-16\">JPQL\u57fa\u790e\uff1a\u30c7\u30fc\u30bf\u691c\u7d22\u306e\u57fa\u672c\u69cb\u6587<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-19\">\u5b9f\u8df5\u7684\u306aJPA\u30c6\u30af\u30cb\u30c3\u30af\u6d3b\u7528<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-20\">\u30ea\u30ec\u30fc\u30b7\u30e7\u30f3\u30b7\u30c3\u30d7\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>      <\/li>      <li>        <a href=\"#i-23\">\u30ad\u30e3\u30c3\u30b7\u30e5\u6226\u7565\u3067\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u6700\u9069\u5316<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-27\">\u73fe\u72b6\u7ba1\u7406\u306e\u5b9f\u88c5\u4f8b<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-31\">JPA\u306e\u6027\u80fd\u6700\u9069\u5316\u3068\u904b\u7528\u306e\u30dd\u30a4\u30f3\u30c8<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-32\">N+1\u554f\u984c\u306e\u89e3\u6c7a\u65b9\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-36\">\u30d0\u30c3\u30c1\u51e6\u7406\u306e\u52b9\u7387\u5316\u624b\u6cd5<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-39\">\u5b9f\u904b\u7528\u3067\u306e\u76e3\u8996\u3068\u30c1\u30e5\u30fc\u30cb\u30f3\u30b0<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-43\">Spring Data JPA \u3068\u306e\u9023\u643a\u5b9f\u73fe<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-44\">\u30ea\u30dd\u30b8\u30c8\u30ea\u306e\u52b9\u679c\u7684\u306a\u8a2d\u8a08\u30d1\u30bf\u30fc\u30f3<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-47\">\u30ab\u30b9\u30bf\u30e0\u30af\u30a8\u30ea\u306e\u5b9f\u88c5\u65b9\u6cd5<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-51\">JPA\u5b9f\u88c5\u306e\u73fe\u5834\u3067\u3088\u304f\u3042\u308b\u30c8\u30e9\u30d6\u30eb\u5bfe\u7b56<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-52\">LazyInitializationException\u306e\u539f\u56e0\u3068\u5bfe\u51e6\u6cd5<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-57\">\u30c7\u30c3\u30c9\u30ed\u30c3\u30af\u56de\u907f\u306e\u305f\u3081\u306e\u30ed\u30c3\u30af\u6226\u7565<\/a>      <\/li>    <\/ul>  <\/li>  <li class=\"last\">    <a href=\"#i-61\">JPA\u3092\u4f7f\u7528\u3057\u305f\u5b9f\u88c5\u4f8b\u3068\u89e3\u8aac<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-62\">EC \u30b5\u30a4\u30c8\u306e\u5546\u54c1\u7ba1\u7406\u30b7\u30b9\u30c6\u30e0\u5b9f\u88c5\u4f8b<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-66\">\u30bd\u30fc\u30b7\u30e3\u30eb\u30e1\u30c7\u30a3\u30a2\u306e\u30bf\u30a4\u30e0\u30e9\u30a4\u30f3\u5b9f\u88c5\u4f8b<\/a>      <\/li>    <\/ul>  <\/li><\/ul>\n      <a href=\"#\" class=\"sgb-toc-button js-toc-button\" rel=\"nofollow\" data-open-dialog=\"true\"><i class=\"fa fa-list\"><\/i><span class=\"sgb-toc-button__text\">\u76ee\u6b21\u3078<\/span><\/a>\n    <\/div><\/div><h2 class=\"wp-block-heading\" id=\"i-1\">JPA\u304c\u89e3\u6c7a\u3059\u308b3\u3064\u306e\u958b\u767a\u8ab2\u984c<\/h2>\n\n\n\n<p>Java\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u958b\u767a\u306b\u304a\u3044\u3066\u3001\u30c7\u30fc\u30bf\u306e\u6c38\u7d9a\u5316\u51e6\u7406\u306f\u5e38\u306b\u91cd\u8981\u306a\u8ab2\u984c\u3068\u306a\u3063\u3066\u3044\u307e\u3059\u3002Java Persistence API\uff08JPA\uff09\u306f\u3001\u3053\u308c\u3089\u306e\u8ab2\u984c\u306b\u5bfe\u3059\u308b\u5305\u62ec\u7684\u306a\u30bd\u30ea\u30e5\u30fc\u30b7\u30e7\u30f3\u3092\u63d0\u4f9b\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-2\">1. \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u3068\u95a2\u4fc2\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306e\u30df\u30b9\u30de\u30c3\u30c1\u89e3\u6d88<\/h3>\n\n\n\n<p>JPA\u306f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3068\u95a2\u4fc2\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306e\u6982\u5ff5\u7684\u306a\u30ae\u30e3\u30c3\u30d7\u3092\u57cb\u3081\u307e\u3059\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u81ea\u52d5\u30de\u30c3\u30d4\u30f3\u30b0\u6a5f\u80fd<\/strong>: Java\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30c6\u30fc\u30d6\u30eb\u3068\u306e\u9593\u306e\u5909\u63db\u3092\u81ea\u52d5\u5316<\/li>\n\n\n\n<li><strong>\u7d99\u627f\u95a2\u4fc2\u306e\u7ba1\u7406<\/strong>: \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u306e\u7d99\u627f\u6982\u5ff5\u3092\u30c6\u30fc\u30d6\u30eb\u8a2d\u8a08\u306b\u53cd\u6620<\/li>\n\n\n\n<li><strong>\u95a2\u9023\u306e\u53cc\u65b9\u5411\u7ba1\u7406<\/strong>: \u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u9593\u306e\u53c2\u7167\u95a2\u4fc2\u3092\u81ea\u52d5\u7684\u306b\u540c\u671f<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-3\">2. \u751f\u7523\u6027\u306e\u5411\u4e0a<\/h3>\n\n\n\n<p>\u958b\u767a\u8005\u306e\u4f5c\u696d\u52b9\u7387\u3092\u5927\u5e45\u306b\u6539\u5584\u3057\u307e\u3059\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u30dc\u30a4\u30e9\u30fc\u30d7\u30ec\u30fc\u30c8\u30b3\u30fc\u30c9\u306e\u524a\u6e1b<\/strong>: \u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u64cd\u4f5c\u306e\u5b9a\u578b\u30b3\u30fc\u30c9\u3092\u6700\u5c0f\u9650\u306b<\/li>\n\n\n\n<li><strong>\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u30d9\u30fc\u30b9\u306e\u8a2d\u5b9a<\/strong>: XML\u8a2d\u5b9a\u30d5\u30a1\u30a4\u30eb\u306e\u8907\u96d1\u3055\u3092\u8efd\u6e1b<\/li>\n\n\n\n<li><strong>Type-safe \u306a\u30af\u30a8\u30ea\u4f5c\u6210<\/strong>: \u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u306e\u30a8\u30e9\u30fc\u30c1\u30a7\u30c3\u30af\u304c\u53ef\u80fd<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-4\">3. \u4fdd\u5b88\u6027\u3068\u30b9\u30b1\u30fc\u30e9\u30d3\u30ea\u30c6\u30a3\u306e\u5411\u4e0a<\/h3>\n\n\n\n<p>\u9577\u671f\u7684\u306a\u904b\u7528\u3092\u898b\u636e\u3048\u305f\u5229\u70b9\u3092\u63d0\u4f9b\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u30d9\u30f3\u30c0\u30fc\u975e\u4f9d\u5b58<\/strong>: \u7279\u5b9a\u306e\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306b\u4f9d\u5b58\u3057\u306a\u3044\u5b9f\u88c5\u304c\u53ef\u80fd<\/li>\n\n\n\n<li><strong>\u30ad\u30e3\u30c3\u30b7\u30e5\u6a5f\u80fd<\/strong>: \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u6700\u9069\u5316\u3092\u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af\u30ec\u30d9\u30eb\u3067\u30b5\u30dd\u30fc\u30c8<\/li>\n\n\n\n<li><strong>\u30c8\u30e9\u30f3\u30b6\u30af\u30b7\u30e7\u30f3\u7ba1\u7406<\/strong>: \u4e00\u8cab\u6027\u306e\u3042\u308b\u30c7\u30fc\u30bf\u64cd\u4f5c\u3092\u5b9f\u73fe<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-5\">\u5f93\u6765\u306eJDBC\u3068\u306e\u6c7a\u5b9a\u7684\u306a\u9055\u3044<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-6\">\u30a2\u30d7\u30ed\u30fc\u30c1\u306e\u6839\u672c\u7684\u306a\u9055\u3044<\/h3>\n\n\n<div id=\"id-5158fcbb-008e-4aeb-9265-c43a284d3fab\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u9805\u76ee<\/th><th>JDBC<\/th><th>JPA<\/th><\/tr><\/thead><tbody><tr><td>\u30c7\u30fc\u30bf\u64cd\u4f5c\u65b9\u6cd5<\/td><td>SQL\u4e2d\u5fc3<\/td><td>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u4e2d\u5fc3<\/td><\/tr><tr><td>\u30b3\u30fc\u30c9\u91cf<\/td><td>\u591a\u3044<\/td><td>\u5c11\u306a\u3044<\/td><\/tr><tr><td>\u5b66\u7fd2\u66f2\u7dda<\/td><td>\u306a\u3060\u3089\u304b<\/td><td>\u521d\u671f\u306f\u6025\u3060\u304c\u9577\u671f\u7684\u306b\u52b9\u7387\u7684<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h3 class=\"wp-block-heading\" id=\"i-7\">\u5177\u4f53\u7684\u306a\u5b9f\u88c5\u306e\u9055\u3044<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30a2\u30af\u30bb\u30b9<\/strong><\/li>\n<\/ol>\n\n\n\n<p>JDBC\u5b9f\u88c5\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">public Customer getCustomer(long id) {\n    Connection conn = null;\n    PreparedStatement stmt = null;\n    ResultSet rs = null;\n    try {\n        conn = getConnection();\n        stmt = conn.prepareStatement(\"SELECT * FROM customers WHERE id = ?\");\n        stmt.setLong(1, id);\n        rs = stmt.executeQuery();\n        if (rs.next()) {\n            Customer customer = new Customer();\n            customer.setId(rs.getLong(\"id\"));\n            customer.setName(rs.getString(\"name\"));\n            return customer;\n        }\n    } catch (SQLException e) {\n        \/\/ \u30a8\u30e9\u30fc\u51e6\u7406\n    } finally {\n        \/\/ \u30ea\u30bd\u30fc\u30b9\u306e\u30af\u30ed\u30fc\u30ba\u51e6\u7406\n    }\n    return null;\n}<\/pre>\n\n\n\n<p>JPA\u5b9f\u88c5\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Entity\npublic class Customer {\n    @Id\n    private Long id;\n    private String name;\n    \/\/ getters and setters\n}\n\npublic Customer getCustomer(long id) {\n    EntityManager em = getEntityManager();\n    return em.find(Customer.class, id);\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-8\">\u4e3b\u8981\u306a\u6539\u5584\u70b9<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u30b3\u30fc\u30c9\u91cf\u306e\u524a\u6e1b<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>JPA\u3067\u306f\u8a2d\u5b9a\u306e\u5927\u90e8\u5206\u3092\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u3067\u884c\u3044\u3001\u5b9f\u969b\u306e\u30c7\u30fc\u30bf\u30a2\u30af\u30bb\u30b9\u30b3\u30fc\u30c9\u3092\u6700\u5c0f\u9650\u306b\u6291\u3048\u3089\u308c\u307e\u3059<\/li>\n\n\n\n<li>\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u30af\u30e9\u30b9\u306e\u5b9a\u7fa9\u3060\u3051\u3067\u57fa\u672c\u7684\u306aCRUD\u64cd\u4f5c\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u30a8\u30e9\u30fc\u51e6\u7406\u306e\u7c21\u7d20\u5316<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>JPA\u3067\u306f\u30c1\u30a7\u30c3\u30af\u4f8b\u5916\u306e\u4ee3\u308f\u308a\u306b\u975e\u30c1\u30a7\u30c3\u30af\u4f8b\u5916\u3092\u4f7f\u7528<\/li>\n\n\n\n<li>\u30c8\u30e9\u30f3\u30b6\u30af\u30b7\u30e7\u30f3\u7ba1\u7406\u304c\u5ba3\u8a00\u7684\u306b\u884c\u3048\u308b<\/li>\n\n\n\n<li>\u30b3\u30cd\u30af\u30b7\u30e7\u30f3\u7ba1\u7406\u3092\u81ea\u52d5\u5316<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u4fdd\u5b88\u6027\u306e\u5411\u4e0a<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u5909\u66f4\u3078\u306e\u8010\u6027\u304c\u9ad8\u3044<\/li>\n\n\n\n<li>\u30ea\u30d5\u30a1\u30af\u30bf\u30ea\u30f3\u30b0\u304c\u5bb9\u6613<\/li>\n\n\n\n<li>\u30c6\u30b9\u30c8\u304c\u66f8\u304d\u3084\u3059\u3044<\/li>\n<\/ul>\n\n\n\n<p>JPA\u306f\u5358\u306a\u308b\u30c7\u30fc\u30bf\u30a2\u30af\u30bb\u30b9\u5c64\u306e\u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af\u3067\u306f\u306a\u304f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306b\u304a\u3051\u308b\u30c7\u30fc\u30bf\u6c38\u7d9a\u5316\u306e\u5305\u62ec\u7684\u306a\u30bd\u30ea\u30e5\u30fc\u30b7\u30e7\u30f3\u3068\u3057\u3066\u6a5f\u80fd\u3057\u307e\u3059\u3002\u7279\u306b\u5927\u898f\u6a21\u306a\u30a8\u30f3\u30bf\u30fc\u30d7\u30e9\u30a4\u30ba\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306b\u304a\u3044\u3066\u3001\u305d\u306e\u4fa1\u5024\u3092\u6700\u5927\u9650\u306b\u767a\u63ee\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-9\">JPA \u306e\u57fa\u672c\u6a5f\u80fd\u3068\u5b9f\u88c5\u624b\u9806<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-10\">\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u30af\u30e9\u30b9\u306e\u4f5c\u6210\u65b9\u6cd5\u3068\u91cd\u8981\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3<\/h2>\n\n\n\n<p>\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u30af\u30e9\u30b9\u306f\u3001\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30c6\u30fc\u30d6\u30eb\u3068Java\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u7d10\u3065\u3051\u308b\u4e2d\u5fc3\u7684\u306a\u8981\u7d20\u3067\u3059\u3002\u4ee5\u4e0b\u306b\u3001\u52b9\u679c\u7684\u306a\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u30af\u30e9\u30b9\u306e\u5b9f\u88c5\u65b9\u6cd5\u3092\u8aac\u660e\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-11\">\u57fa\u672c\u7684\u306a\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u30af\u30e9\u30b9\u306e\u5b9f\u88c5<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Entity\n@Table(name = \"employees\")\npublic class Employee {\n    @Id\n    @GeneratedValue(strategy = GenerationType.IDENTITY)\n    private Long id;\n\n    @Column(name = \"first_name\", nullable = false, length = 50)\n    private String firstName;\n\n    @Column(name = \"last_name\", nullable = false, length = 50)\n    private String lastName;\n\n    @Temporal(TemporalType.DATE)\n    private Date birthDate;\n\n    @Enumerated(EnumType.STRING)\n    private EmployeeStatus status;\n\n    \/\/ getters and setters\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-12\">\u91cd\u8981\u306a\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u306e\u89e3\u8aac<\/h3>\n\n\n<div id=\"id-a53f16c6-ed74-45e2-b066-bc1079f70f2c\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3<\/th><th>\u7528\u9014<\/th><th>\u4e3b\u306a\u5c5e\u6027<\/th><\/tr><\/thead><tbody><tr><td>@Entity<\/td><td>\u30af\u30e9\u30b9\u3092\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u3068\u3057\u3066\u5b9a\u7fa9<\/td><td>name: \u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u540d<\/td><\/tr><tr><td>@Table<\/td><td>\u30de\u30c3\u30d4\u30f3\u30b0\u3059\u308b\u30c6\u30fc\u30d6\u30eb\u3092\u6307\u5b9a<\/td><td>name: \u30c6\u30fc\u30d6\u30eb\u540d<\/td><\/tr><tr><td>@Id<\/td><td>\u4e3b\u30ad\u30fc\u30d5\u30a3\u30fc\u30eb\u30c9\u3092\u6307\u5b9a<\/td><td>\u2013<\/td><\/tr><tr><td>@GeneratedValue<\/td><td>\u4e3b\u30ad\u30fc\u306e\u751f\u6210\u6226\u7565\u3092\u5b9a\u7fa9<\/td><td>strategy: \u751f\u6210\u65b9\u5f0f<\/td><\/tr><tr><td>@Column<\/td><td>\u30ab\u30e9\u30e0\u5c5e\u6027\u306e\u8a73\u7d30\u8a2d\u5b9a<\/td><td>name, nullable, length \u306a\u3069<\/td><\/tr><tr><td>@Temporal<\/td><td>\u65e5\u4ed8\u578b\u306e\u30de\u30c3\u30d4\u30f3\u30b0\u8a2d\u5b9a<\/td><td>TemporalType\u5217\u6319\u578b<\/td><\/tr><tr><td>@Enumerated<\/td><td>\u5217\u6319\u578b\u306e\u30de\u30c3\u30d4\u30f3\u30b0\u65b9\u6cd5<\/td><td>EnumType.ORDINAL\/STRING<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\" id=\"i-13\">EntityManager \u306e\u52b9\u679c\u7684\u306a\u4f7f\u3044\u65b9<\/h2>\n\n\n\n<p>EntityManager\u306f\u3001\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306e\u6c38\u7d9a\u5316\u64cd\u4f5c\u3092\u62c5\u3046\u4e2d\u6838\u7684\u306a\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-14\">\u57fa\u672c\u7684\u306aCRUD\u64cd\u4f5c<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Repository\npublic class EmployeeRepository {\n    @PersistenceContext\n    private EntityManager entityManager;\n\n    \/\/ Create\n    public void save(Employee employee) {\n        entityManager.persist(employee);\n    }\n\n    \/\/ Read\n    public Employee find(Long id) {\n        return entityManager.find(Employee.class, id);\n    }\n\n    \/\/ Update\n    public Employee update(Employee employee) {\n        return entityManager.merge(employee);\n    }\n\n    \/\/ Delete\n    public void delete(Long id) {\n        Employee employee = find(id);\n        if (employee != null) {\n            entityManager.remove(employee);\n        }\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-15\">EntityManager\u306e\u30e9\u30a4\u30d5\u30b5\u30a4\u30af\u30eb\u7ba1\u7406<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Service\n@Transactional\npublic class EmployeeService {\n    @Autowired\n    private EmployeeRepository repository;\n\n    public void updateEmployeeStatus(Long id, EmployeeStatus newStatus) {\n        Employee employee = repository.find(id);\n        if (employee != null) {\n            employee.setStatus(newStatus);\n            \/\/ \u660e\u793a\u7684\u306amerge\u4e0d\u8981\uff08@Transactional\u306b\u3088\u308a\u81ea\u52d5\u7684\u306b\u53cd\u6620\uff09\n        }\n    }\n}<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-16\">JPQL\u57fa\u790e\uff1a\u30c7\u30fc\u30bf\u691c\u7d22\u306e\u57fa\u672c\u69cb\u6587<\/h2>\n\n\n\n<p>JPQL\u306f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u7684\u306a\u30af\u30a8\u30ea\u8a00\u8a9e\u3067\u3001\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306b\u5bfe\u3057\u3066\u64cd\u4f5c\u3092\u884c\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-17\">\u57fa\u672c\u7684\u306aJPQL\u30af\u30a8\u30ea\u4f8b<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">public class EmployeeQueryRepository {\n    @PersistenceContext\n    private EntityManager em;\n\n    \/\/ \u5358\u7d14\u306a\u691c\u7d22\u30af\u30a8\u30ea\n    public List&lt;Employee&gt; findByLastName(String lastName) {\n        return em.createQuery(\n            \"SELECT e FROM Employee e WHERE e.lastName = :lastName\",\n            Employee.class)\n            .setParameter(\"lastName\", lastName)\n            .getResultList();\n    }\n\n    \/\/ \u96c6\u7d04\u95a2\u6570\u3092\u4f7f\u7528\u3057\u305f\u30af\u30a8\u30ea\n    public Double getAverageAge() {\n        return em.createQuery(\n            \"SELECT AVG(YEAR(CURRENT_DATE) - YEAR(e.birthDate)) \" +\n            \"FROM Employee e\", Double.class)\n            .getSingleResult();\n    }\n\n    \/\/ JOIN \u3092\u4f7f\u7528\u3057\u305f\u30af\u30a8\u30ea\n    public List&lt;Employee&gt; findByDepartment(String deptName) {\n        return em.createQuery(\n            \"SELECT e FROM Employee e \" +\n            \"JOIN e.department d \" +\n            \"WHERE d.name = :deptName\", Employee.class)\n            .setParameter(\"deptName\", deptName)\n            .getResultList();\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-18\">JPQL\u306e\u4e3b\u8981\u306a\u6a5f\u80fd<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u96c6\u7d04\u95a2\u6570<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>COUNT, SUM, AVG, MAX, MIN<\/li>\n\n\n\n<li>GROUP BY, HAVING\u53e5\u306e\u30b5\u30dd\u30fc\u30c8<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u7d50\u5408\u64cd\u4f5c<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>INNER JOIN<\/li>\n\n\n\n<li>LEFT\/RIGHT OUTER JOIN<\/li>\n\n\n\n<li>FETCH JOIN\uff08N+1\u554f\u984c\u306e\u89e3\u6c7a\uff09<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u30b5\u30d6\u30af\u30a8\u30ea<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   \"SELECT e FROM Employee e WHERE e.salary &gt; \" +\n   \"(SELECT AVG(e2.salary) FROM Employee e2)\"<\/pre>\n\n\n\n<ol start=\"4\" class=\"wp-block-list\">\n<li><strong>\u52d5\u7684\u30af\u30a8\u30ea\u30d3\u30eb\u30c9<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   public List&lt;Employee&gt; searchEmployees(String firstName, String lastName, \n                                       EmployeeStatus status) {\n       CriteriaBuilder cb = em.getCriteriaBuilder();\n       CriteriaQuery&lt;Employee&gt; query = cb.createQuery(Employee.class);\n       Root&lt;Employee&gt; employee = query.from(Employee.class);\n\n       List&lt;Predicate&gt; predicates = new ArrayList&lt;&gt;();\n\n       if (firstName != null) {\n           predicates.add(cb.like(employee.get(\"firstName\"), firstName + \"%\"));\n       }\n       if (lastName != null) {\n           predicates.add(cb.like(employee.get(\"lastName\"), lastName + \"%\"));\n       }\n       if (status != null) {\n           predicates.add(cb.equal(employee.get(\"status\"), status));\n       }\n\n       query.where(predicates.toArray(new Predicate[0]));\n       return em.createQuery(query).getResultList();\n   }<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u57fa\u672c\u6a5f\u80fd\u3092\u9069\u5207\u306b\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u52b9\u7387\u7684\u306a\u30c7\u30fc\u30bf\u30a2\u30af\u30bb\u30b9\u5c64\u3092\u69cb\u7bc9\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3053\u308c\u3089\u306e\u57fa\u672c\u6a5f\u80fd\u3092\u6d3b\u7528\u3057\u305f\u5b9f\u8df5\u7684\u306a\u30c6\u30af\u30cb\u30c3\u30af\u306b\u3064\u3044\u3066\u8aac\u660e\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-19\">\u5b9f\u8df5\u7684\u306aJPA\u30c6\u30af\u30cb\u30c3\u30af\u6d3b\u7528<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-20\">\u30ea\u30ec\u30fc\u30b7\u30e7\u30f3\u30b7\u30c3\u30d7\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h2>\n\n\n\n<p>\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u9593\u306e\u95a2\u9023\u3092\u9069\u5207\u306b\u7ba1\u7406\u3059\u308b\u3053\u3068\u306f\u3001JPA\u3092\u52b9\u679c\u7684\u306b\u6d3b\u7528\u3059\u308b\u4e0a\u3067\u91cd\u8981\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-21\">\u53cc\u65b9\u5411\u95a2\u9023\u306e\u5b9f\u88c5<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Entity\npublic class Department {\n    @Id\n    @GeneratedValue(strategy = GenerationType.IDENTITY)\n    private Long id;\n\n    private String name;\n\n    @OneToMany(mappedBy = \"department\", cascade = CascadeType.ALL, orphanRemoval = true)\n    private List&lt;Employee&gt; employees = new ArrayList&lt;&gt;();\n\n    \/\/ \u95a2\u9023\u7ba1\u7406\u7528\u306e\u30e6\u30fc\u30c6\u30a3\u30ea\u30c6\u30a3\u30e1\u30bd\u30c3\u30c9\n    public void addEmployee(Employee employee) {\n        employees.add(employee);\n        employee.setDepartment(this);\n    }\n\n    public void removeEmployee(Employee employee) {\n        employees.remove(employee);\n        employee.setDepartment(null);\n    }\n}\n\n@Entity\npublic class Employee {\n    @Id\n    @GeneratedValue(strategy = GenerationType.IDENTITY)\n    private Long id;\n\n    @ManyToOne(fetch = FetchType.LAZY)\n    @JoinColumn(name = \"department_id\")\n    private Department department;\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-22\">\u95a2\u9023\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u30ab\u30b9\u30b1\u30fc\u30c9\u64cd\u4f5c\u306e\u9069\u5207\u306a\u8a2d\u5b9a<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   @OneToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE})\n   private List&lt;Address&gt; addresses;<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li><strong>Fetch\u578b\u306e\u6700\u9069\u5316<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   \/\/ \u983b\u7e41\u306b\u30a2\u30af\u30bb\u30b9\u3059\u308b\u95a2\u9023\n   @ManyToOne(fetch = FetchType.EAGER)\n   private Company company;\n\n   \/\/ \u5fc5\u8981\u6642\u306e\u307f\u53d6\u5f97\u3059\u308b\u95a2\u9023\n   @OneToMany(fetch = FetchType.LAZY)\n   private List&lt;Project&gt; projects;<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li><strong>\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u578b\u306e\u9078\u629e<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   \/\/ \u9806\u5e8f\u304c\u91cd\u8981\u306a\u5834\u5408\n   @OneToMany\n   private List&lt;Task&gt; tasks;\n\n   \/\/ \u91cd\u8907\u3092\u8a31\u53ef\u3057\u306a\u3044\u5834\u5408\n   @OneToMany\n   private Set&lt;Skill&gt; skills;<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-23\">\u30ad\u30e3\u30c3\u30b7\u30e5\u6226\u7565\u3067\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u6700\u9069\u5316<\/h2>\n\n\n\n<p>JPA\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u6a5f\u80fd\u3092\u52b9\u679c\u7684\u306b\u6d3b\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u5927\u5e45\u306b\u5411\u4e0a\u3055\u305b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-24\">1\u6b21\u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u6d3b\u7528<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Service\n@Transactional\npublic class EmployeeService {\n    @PersistenceContext\n    private EntityManager em;\n\n    public Employee getEmployee(Long id) {\n        \/\/ \u540c\u4e00\u30c8\u30e9\u30f3\u30b6\u30af\u30b7\u30e7\u30f3\u5185\u3067\u306f1\u6b21\u30ad\u30e3\u30c3\u30b7\u30e5\u304b\u3089\u53d6\u5f97\n        Employee emp = em.find(Employee.class, id);\n        return emp;\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-25\">2\u6b21\u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u8a2d\u5b9a<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Entity\n@Cache(usage = CacheConcurrencyStrategy.READ_WRITE)\npublic class Department {\n    @Id\n    private Long id;\n\n    @Cache(usage = CacheConcurrencyStrategy.READ_ONLY)\n    @OneToMany(mappedBy = \"department\")\n    private List&lt;Employee&gt; employees;\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-26\">\u30ad\u30e3\u30c3\u30b7\u30e5\u6226\u7565\u306e\u9078\u629e\u57fa\u6e96<\/h3>\n\n\n<div id=\"id-380077d0-4c53-495f-88ee-f5cb14bd8a89\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u30c7\u30fc\u30bf\u306e\u7279\u6027<\/th><th>\u63a8\u5968\u30ad\u30e3\u30c3\u30b7\u30e5\u6226\u7565<\/th><th>\u4f7f\u7528\u4f8b<\/th><\/tr><\/thead><tbody><tr><td>\u53c2\u7167\u306e\u307f<\/td><td>READ_ONLY<\/td><td>\u30de\u30b9\u30bf\u30fc\u30c7\u30fc\u30bf<\/td><\/tr><tr><td>\u66f4\u65b0\u983b\u5ea6\u4f4e<\/td><td>NONSTRICT_READ_WRITE<\/td><td>\u90e8\u7f72\u60c5\u5831<\/td><\/tr><tr><td>\u66f4\u65b0\u983b\u5ea6\u9ad8<\/td><td>READ_WRITE<\/td><td>\u6ce8\u6587\u60c5\u5831<\/td><\/tr><tr><td>\u66f4\u65b0\u7af6\u5408\u591a<\/td><td>TRANSACTIONAL<\/td><td>\u5728\u5eab\u6570<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<h2 class=\"wp-block-heading\" id=\"i-27\">\u73fe\u72b6\u7ba1\u7406\u306e\u5b9f\u88c5\u4f8b<\/h2>\n\n\n\n<p>\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306e\u72b6\u614b\u3092\u9069\u5207\u306b\u7ba1\u7406\u3059\u308b\u3053\u3068\u306f\u3001\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u4fe1\u983c\u6027\u5411\u4e0a\u306b\u76f4\u7d50\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-28\">\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306e\u72b6\u614b\u9077\u79fb\u7ba1\u7406<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Entity\npublic class Order {\n    @Enumerated(EnumType.STRING)\n    private OrderStatus status;\n\n    @Version\n    private Long version;\n\n    \/\/ \u72b6\u614b\u9077\u79fb\u3092\u5236\u5fa1\u3059\u308b\u30d3\u30b8\u30cd\u30b9\u30e1\u30bd\u30c3\u30c9\n    public void confirm() {\n        if (status != OrderStatus.PENDING) {\n            throw new IllegalStateException(\"Order must be in PENDING state\");\n        }\n        status = OrderStatus.CONFIRMED;\n    }\n\n    public void ship() {\n        if (status != OrderStatus.CONFIRMED) {\n            throw new IllegalStateException(\"Order must be in CONFIRMED state\");\n        }\n        status = OrderStatus.SHIPPED;\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-29\">\u697d\u89b3\u7684\u30ed\u30c3\u30af\u306e\u5b9f\u88c5<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Service\n@Transactional\npublic class OrderService {\n    @PersistenceContext\n    private EntityManager em;\n\n    public void updateOrderAmount(Long orderId, BigDecimal newAmount) {\n        try {\n            Order order = em.find(Order.class, orderId);\n            order.setAmount(newAmount);\n            em.flush(); \/\/ \u30d0\u30fc\u30b8\u30e7\u30f3\u30c1\u30a7\u30c3\u30af\u3092\u5f37\u5236\n        } catch (OptimisticLockException e) {\n            \/\/ \u7af6\u5408\u304c\u691c\u51fa\u3055\u308c\u305f\u5834\u5408\u306e\u51e6\u7406\n            throw new BusinessException(\"Order was modified by another user\");\n        }\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-30\">\u76e3\u67fb\u60c5\u5831\u306e\u81ea\u52d5\u7ba1\u7406<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@EntityListeners(AuditingEntityListener.class)\n@MappedSuperclass\npublic abstract class Auditable {\n    @CreatedDate\n    private LocalDateTime createdAt;\n\n    @LastModifiedDate\n    private LocalDateTime updatedAt;\n\n    @CreatedBy\n    private String createdBy;\n\n    @LastModifiedBy\n    private String updatedBy;\n}\n\n@Entity\npublic class Order extends Auditable {\n    \/\/ \u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u56fa\u6709\u306e\u30d5\u30a3\u30fc\u30eb\u30c9\n}<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u5b9f\u8df5\u7684\u306a\u30c6\u30af\u30cb\u30c3\u30af\u3092\u9069\u5207\u306b\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u5805\u7262\u3067\u4fdd\u5b88\u6027\u306e\u9ad8\u3044\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3092\u69cb\u7bc9\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3053\u308c\u3089\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3092\u6d3b\u7528\u3059\u308b\u969b\u306e\u6027\u80fd\u6700\u9069\u5316\u3068\u904b\u7528\u306e\u30dd\u30a4\u30f3\u30c8\u306b\u3064\u3044\u3066\u8aac\u660e\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-31\">JPA\u306e\u6027\u80fd\u6700\u9069\u5316\u3068\u904b\u7528\u306e\u30dd\u30a4\u30f3\u30c8<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-32\">N+1\u554f\u984c\u306e\u89e3\u6c7a\u65b9\u6cd5<\/h2>\n\n\n\n<p>N+1\u554f\u984c\u306f\u3001JPA\u3092\u4f7f\u7528\u3059\u308b\u969b\u306b\u3088\u304f\u906d\u9047\u3059\u308b\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u554f\u984c\u306e\u4e00\u3064\u3067\u3059\u3002\u3053\u306e\u554f\u984c\u306f\u30011\u56de\u306e\u30af\u30a8\u30ea\u3067\u53d6\u5f97\u3057\u305f\u7d50\u679c\u306b\u5bfe\u3057\u3066\u3001\u95a2\u9023\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u3092\u53d6\u5f97\u3059\u308b\u305f\u3081\u306b\u8ffd\u52a0\u306e\u30af\u30a8\u30ea\u304c\u5b9f\u884c\u3055\u308c\u308b\u73fe\u8c61\u3092\u6307\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-33\">\u554f\u984c\u304c\u767a\u751f\u3059\u308b\u30b1\u30fc\u30b9<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ N+1\u554f\u984c\u304c\u767a\u751f\u3059\u308b\u30b3\u30fc\u30c9\u4f8b\n@Entity\npublic class Department {\n    @OneToMany(mappedBy = \"department\")\n    private List&lt;Employee&gt; employees;\n}\n\n\/\/ \u4ee5\u4e0b\u306e\u30b3\u30fc\u30c9\u3067N+1\u554f\u984c\u304c\u767a\u751f\nList&lt;Department&gt; departments = em.createQuery(\n    \"SELECT d FROM Department d\", Department.class).getResultList();\nfor (Department dept : departments) {\n    System.out.println(\"Employees: \" + dept.getEmployees().size()); \/\/ \u8ffd\u52a0\u30af\u30a8\u30ea\u304c\u767a\u751f\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-34\">\u89e3\u6c7a\u65b9\u6cd51: JOIN FETCH \u306e\u4f7f\u7528<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ JOIN FETCH\u3092\u4f7f\u7528\u3057\u305f\u89e3\u6c7a\u7b56\n@Repository\npublic class DepartmentRepository {\n    public List&lt;Department&gt; findAllWithEmployees() {\n        return em.createQuery(\n            \"SELECT DISTINCT d FROM Department d \" +\n            \"LEFT JOIN FETCH d.employees\", Department.class)\n            .getResultList();\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-35\">\u89e3\u6c7a\u65b9\u6cd52: EntityGraph\u306e\u6d3b\u7528<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Entity\n@NamedEntityGraph(\n    name = \"Department.withEmployees\",\n    attributeNodes = @NamedAttributeNode(\"employees\")\n)\npublic class Department {\n    \/\/ \u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306e\u5b9a\u7fa9\n}\n\n\/\/ EntityGraph\u306e\u4f7f\u7528\npublic List&lt;Department&gt; findAllUsingEntityGraph() {\n    EntityGraph&lt;?&gt; graph = em.getEntityGraph(\"Department.withEmployees\");\n    return em.createQuery(\"SELECT d FROM Department d\", Department.class)\n        .setHint(\"javax.persistence.loadgraph\", graph)\n        .getResultList();\n}<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-36\">\u30d0\u30c3\u30c1\u51e6\u7406\u306e\u52b9\u7387\u5316\u624b\u6cd5<\/h2>\n\n\n\n<p>\u5927\u91cf\u306e\u30c7\u30fc\u30bf\u3092\u51e6\u7406\u3059\u308b\u969b\u306f\u3001\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u6700\u9069\u5316\u304c\u91cd\u8981\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-37\">\u30d0\u30c3\u30c1\u30b5\u30a4\u30ba\u306e\u6700\u9069\u5316<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Service\n@Transactional\npublic class DataImportService {\n    private static final int BATCH_SIZE = 50;\n\n    @PersistenceContext\n    private EntityManager em;\n\n    public void importEmployees(List&lt;EmployeeDTO&gt; employeeDTOs) {\n        int count = 0;\n        for (EmployeeDTO dto : employeeDTOs) {\n            Employee employee = new Employee();\n            employee.setName(dto.getName());\n            em.persist(employee);\n\n            if (++count % BATCH_SIZE == 0) {\n                em.flush();\n                em.clear(); \/\/ \u6c38\u7d9a\u5316\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u306e\u30af\u30ea\u30a2\n            }\n        }\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-38\">JPQL BULK\u30a2\u30c3\u30d7\u30c7\u30fc\u30c8\u306e\u6d3b\u7528<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Repository\npublic class EmployeeRepository {\n    public int updateEmployeeStatus(EmployeeStatus oldStatus, \n                                  EmployeeStatus newStatus) {\n        return em.createQuery(\n            \"UPDATE Employee e SET e.status = :newStatus \" +\n            \"WHERE e.status = :oldStatus\")\n            .setParameter(\"newStatus\", newStatus)\n            .setParameter(\"oldStatus\", oldStatus)\n            .executeUpdate();\n    }\n}<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-39\">\u5b9f\u904b\u7528\u3067\u306e\u76e3\u8996\u3068\u30c1\u30e5\u30fc\u30cb\u30f3\u30b0<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-40\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u76e3\u8996\u306e\u5b9f\u88c5<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Aspect\n@Component\npublic class JPAPerformanceMonitor {\n    private static final Logger log = \n        LoggerFactory.getLogger(JPAPerformanceMonitor.class);\n\n    @Around(\"execution(* org.springframework.data.jpa.repository.JpaRepository+.*(..))\")\n    public Object monitorRepositoryMethods(ProceedingJoinPoint pjp) \n            throws Throwable {\n        long start = System.currentTimeMillis();\n        Object result = pjp.proceed();\n        long executionTime = System.currentTimeMillis() - start;\n\n        log.info(\"Method: {} executed in {} ms\",\n                 pjp.getSignature().getName(), executionTime);\n\n        return result;\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-41\">\u7d71\u8a08\u60c5\u5831\u306e\u53ce\u96c6<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Configuration\npublic class JPAConfig {\n    @Bean\n    public JpaVendorAdapter jpaVendorAdapter() {\n        HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();\n        adapter.setShowSql(true);\n        adapter.setGenerateDdl(true);\n        return adapter;\n    }\n\n    @Bean\n    public Properties hibernateProperties() {\n        Properties props = new Properties();\n        props.setProperty(\"hibernate.generate_statistics\", \"true\");\n        props.setProperty(\"hibernate.session.events.log.LOG_QUERIES_SLOWER_THAN_MS\", \"25\");\n        return props;\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-42\">\u30c1\u30e5\u30fc\u30cb\u30f3\u30b0\u306e\u30dd\u30a4\u30f3\u30c8<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u6700\u9069\u5316<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   @Entity\n   @Table(indexes = {\n       @Index(name = \"idx_employee_dept\", columnList = \"department_id\"),\n       @Index(name = \"idx_employee_status\", columnList = \"status\")\n   })\n   public class Employee {\n       \/\/ \u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306e\u5b9a\u7fa9\n   }<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li><strong>\u30af\u30a8\u30ea\u30d2\u30f3\u30c8\u6d3b\u7528<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   public List&lt;Employee&gt; findActiveEmployees() {\n       return em.createQuery(\n           \"SELECT e FROM Employee e WHERE e.status = :status\", \n           Employee.class)\n           .setHint(\"org.hibernate.readOnly\", true)\n           .setHint(\"org.hibernate.fetchSize\", 100)\n           .setParameter(\"status\", EmployeeStatus.ACTIVE)\n           .getResultList();\n   }<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li><strong>\u30ad\u30e3\u30c3\u30b7\u30e5\u8a2d\u5b9a\u306e\u6700\u9069\u5316<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">   # application.properties\n   spring.jpa.properties.hibernate.cache.use_second_level_cache=true\n   spring.jpa.properties.hibernate.cache.region.factory_class=org.hibernate.cache.ehcache.EhCacheRegionFactory\n   spring.jpa.properties.hibernate.cache.use_query_cache=true<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u6700\u9069\u5316\u3068\u904b\u7528\u30dd\u30a4\u30f3\u30c8\u3092\u9069\u5207\u306b\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u9ad8\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3067\u5b89\u5b9a\u3057\u305fJPA\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3092\u5b9f\u73fe\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001Spring Data JPA\u3068\u306e\u9023\u643a\u306b\u3064\u3044\u3066\u8aac\u660e\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-43\">Spring Data JPA \u3068\u306e\u9023\u643a\u5b9f\u73fe<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-44\">\u30ea\u30dd\u30b8\u30c8\u30ea\u306e\u52b9\u679c\u7684\u306a\u8a2d\u8a08\u30d1\u30bf\u30fc\u30f3<\/h2>\n\n\n\n<p>Spring Data JPA\u306f\u3001\u30c7\u30fc\u30bf\u30a2\u30af\u30bb\u30b9\u5c64\u306e\u5b9f\u88c5\u3092\u5927\u5e45\u306b\u7c21\u7d20\u5316\u3057\u307e\u3059\u3002\u9069\u5207\u306a\u8a2d\u8a08\u30d1\u30bf\u30fc\u30f3\u3092\u6d3b\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u30e1\u30f3\u30c6\u30ca\u30f3\u30b9\u6027\u306e\u9ad8\u3044\u30b3\u30fc\u30c9\u3092\u5b9f\u73fe\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-45\">\u57fa\u672c\u7684\u306a\u30ea\u30dd\u30b8\u30c8\u30ea\u306e\u69cb\u6210<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Repository\npublic interface EmployeeRepository \n    extends JpaRepository&lt;Employee, Long&gt; {\n\n    \/\/ \u30e1\u30bd\u30c3\u30c9\u540d\u306b\u3088\u308b\u81ea\u52d5\u30af\u30a8\u30ea\u751f\u6210\n    List&lt;Employee&gt; findByDepartmentNameAndStatus(\n        String departmentName, \n        EmployeeStatus status\n    );\n\n    \/\/ \u30ab\u30a6\u30f3\u30c8\u30af\u30a8\u30ea\n    long countByStatus(EmployeeStatus status);\n\n    \/\/ \u5b58\u5728\u78ba\u8a8d\n    boolean existsByEmail(String email);\n\n    \/\/ \u524a\u9664\u64cd\u4f5c\n    void deleteByStatus(EmployeeStatus status);\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-46\">\u30ea\u30dd\u30b8\u30c8\u30ea\u306e\u968e\u5c64\u5316<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u57fa\u672c\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\n@NoRepositoryBean\npublic interface BaseRepository&lt;T, ID&gt; extends JpaRepository&lt;T, ID&gt; {\n    Optional&lt;T&gt; findByIdAndDeletedFalse(ID id);\n    List&lt;T&gt; findAllByDeletedFalse();\n}\n\n\/\/ \u76e3\u67fb\u6a5f\u80fd\u4ed8\u304d\u30ea\u30dd\u30b8\u30c8\u30ea\n@NoRepositoryBean\npublic interface AuditableRepository&lt;T extends Auditable, ID&gt; \n    extends BaseRepository&lt;T, ID&gt; {\n    List&lt;T&gt; findByCreatedByOrderByCreatedDateDesc(String creator);\n}\n\n\/\/ \u5177\u4f53\u7684\u306a\u30ea\u30dd\u30b8\u30c8\u30ea\n@Repository\npublic interface EmployeeRepository \n    extends AuditableRepository&lt;Employee, Long&gt; {\n    \/\/ \u7279\u5b9a\u306e\u30d3\u30b8\u30cd\u30b9\u30c9\u30e1\u30a4\u30f3\u7528\u306e\u30e1\u30bd\u30c3\u30c9\n}<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-47\">\u30ab\u30b9\u30bf\u30e0\u30af\u30a8\u30ea\u306e\u5b9f\u88c5\u65b9\u6cd5<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-48\">@Query \u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u306e\u6d3b\u7528<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Repository\npublic interface ProjectRepository extends JpaRepository&lt;Project, Long&gt; {\n\n    @Query(\"SELECT p FROM Project p WHERE p.status = :status \" +\n           \"AND p.deadline &lt; :deadline\")\n    List&lt;Project&gt; findUpcomingProjects(\n        @Param(\"status\") ProjectStatus status,\n        @Param(\"deadline\") LocalDate deadline\n    );\n\n    @Query(value = \"SELECT * FROM projects p \" +\n           \"WHERE p.manager_id = :managerId \" +\n           \"ORDER BY deadline ASC LIMIT :limit\",\n           nativeQuery = true)\n    List&lt;Project&gt; findManagerProjects(\n        @Param(\"managerId\") Long managerId,\n        @Param(\"limit\") int limit\n    );\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-49\">\u30ab\u30b9\u30bf\u30e0\u30ea\u30dd\u30b8\u30c8\u30ea\u306e\u5b9f\u88c5<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30ab\u30b9\u30bf\u30e0\u30ea\u30dd\u30b8\u30c8\u30ea\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\npublic interface CustomEmployeeRepository {\n    List&lt;Employee&gt; findByComplexCriteria(\n        EmployeeSearchCriteria criteria\n    );\n}\n\n\/\/ \u5b9f\u88c5\u30af\u30e9\u30b9\n@Repository\npublic class CustomEmployeeRepositoryImpl \n    implements CustomEmployeeRepository {\n\n    @PersistenceContext\n    private EntityManager em;\n\n    @Override\n    public List&lt;Employee&gt; findByComplexCriteria(\n        EmployeeSearchCriteria criteria\n    ) {\n        CriteriaBuilder cb = em.getCriteriaBuilder();\n        CriteriaQuery&lt;Employee&gt; query = cb.createQuery(Employee.class);\n        Root&lt;Employee&gt; root = query.from(Employee.class);\n\n        List&lt;Predicate&gt; predicates = new ArrayList&lt;&gt;();\n\n        if (criteria.getDepartment() != null) {\n            predicates.add(cb.equal(\n                root.get(\"department\"), \n                criteria.getDepartment()\n            ));\n        }\n\n        if (criteria.getSkills() != null &amp;&amp; !criteria.getSkills().isEmpty()) {\n            predicates.add(root.join(\"skills\").in(criteria.getSkills()));\n        }\n\n        query.where(predicates.toArray(new Predicate[0]));\n        return em.createQuery(query).getResultList();\n    }\n}\n\n\/\/ \u30e1\u30a4\u30f3\u30ea\u30dd\u30b8\u30c8\u30ea\n@Repository\npublic interface EmployeeRepository extends \n    JpaRepository&lt;Employee, Long&gt;, \n    CustomEmployeeRepository {\n    \/\/ \u6a19\u6e96\u30e1\u30bd\u30c3\u30c9\u3068\u30ab\u30b9\u30bf\u30e0\u30e1\u30bd\u30c3\u30c9\u3092\u7d71\u5408\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-50\">\u5b9f\u7528\u7684\u306a\u30af\u30a8\u30ea\u4f8b<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Repository\npublic interface EmployeeRepository extends JpaRepository&lt;Employee, Long&gt; {\n\n    \/\/ \u30da\u30fc\u30b8\u30f3\u30b0\u51e6\u7406\n    Page&lt;Employee&gt; findByDepartment(\n        Department department, \n        Pageable pageable\n    );\n\n    \/\/ \u4e26\u3079\u66ff\u3048\n    List&lt;Employee&gt; findByStatusOrderBySalaryDesc(\n        EmployeeStatus status\n    );\n\n    \/\/ \u96c6\u8a08\n    @Query(\"SELECT new com.example.dto.DepartmentStats(\" +\n           \"e.department, COUNT(e), AVG(e.salary)) \" +\n           \"FROM Employee e GROUP BY e.department\")\n    List&lt;DepartmentStats&gt; getDepartmentStatistics();\n\n    \/\/ \u52d5\u7684\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\n    @Query(\"SELECT e FROM Employee e WHERE \" +\n           \"(:department IS NULL OR e.department = :department) AND \" +\n           \"(:status IS NULL OR e.status = :status)\")\n    List&lt;Employee&gt; findByFilters(\n        @Param(\"department\") Department department,\n        @Param(\"status\") EmployeeStatus status\n    );\n}<\/pre>\n\n\n\n<p>\u30ea\u30dd\u30b8\u30c8\u30ea\u306e\u30e1\u30bd\u30c3\u30c9\u547d\u540d\u898f\u5247\u306f\u3001\u4ee5\u4e0b\u306e\u30d1\u30bf\u30fc\u30f3\u306b\u5f93\u3044\u307e\u3059\uff1a<\/p>\n\n\n<div id=\"id-7d4d560f-4ebd-452e-b2e6-3a14bc549c0e\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u30d7\u30ec\u30d5\u30a3\u30c3\u30af\u30b9<\/th><th>\u7528\u9014<\/th><th>\u4f8b<\/th><\/tr><\/thead><tbody><tr><td>findBy<\/td><td>\u691c\u7d22<\/td><td>findByLastName<\/td><\/tr><tr><td>countBy<\/td><td>\u30ab\u30a6\u30f3\u30c8<\/td><td>countByStatus<\/td><\/tr><tr><td>existsBy<\/td><td>\u5b58\u5728\u78ba\u8a8d<\/td><td>existsByEmail<\/td><\/tr><tr><td>deleteBy<\/td><td>\u524a\u9664<\/td><td>deleteByStatus<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n\n\n<p>\u3053\u308c\u3089\u306e\u30d1\u30bf\u30fc\u30f3\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u30c7\u30fc\u30bf\u30a2\u30af\u30bb\u30b9\u5c64\u3092\u52b9\u7387\u7684\u306b\u5b9f\u88c5\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u5b9f\u969b\u306e\u904b\u7528\u3067\u906d\u9047\u3059\u308b\u53ef\u80fd\u6027\u306e\u3042\u308b\u30c8\u30e9\u30d6\u30eb\u3068\u305d\u306e\u5bfe\u7b56\u306b\u3064\u3044\u3066\u8aac\u660e\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-51\">JPA\u5b9f\u88c5\u306e\u73fe\u5834\u3067\u3088\u304f\u3042\u308b\u30c8\u30e9\u30d6\u30eb\u5bfe\u7b56<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-52\">LazyInitializationException\u306e\u539f\u56e0\u3068\u5bfe\u51e6\u6cd5<\/h2>\n\n\n\n<p>LazyInitializationException\u306f\u3001JPA\u3092\u4f7f\u7528\u3059\u308b\u958b\u767a\u8005\u304c\u6700\u3082\u983b\u7e41\u306b\u906d\u9047\u3059\u308b\u4f8b\u5916\u306e\u4e00\u3064\u3067\u3059\u3002\u3053\u306e\u554f\u984c\u306f\u3001\u9045\u5ef6\u30ed\u30fc\u30c9\u3055\u308c\u308b\u95a2\u9023\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306b\u30bb\u30c3\u30b7\u30e7\u30f3\u5916\u3067\u30a2\u30af\u30bb\u30b9\u3057\u3088\u3046\u3068\u3057\u305f\u969b\u306b\u767a\u751f\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-53\">\u554f\u984c\u304c\u767a\u751f\u3059\u308b\u30b7\u30ca\u30ea\u30aa<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Entity\npublic class Department {\n    @OneToMany(mappedBy = \"department\", fetch = FetchType.LAZY)\n    private List&lt;Employee&gt; employees;\n}\n\n@Service\n@Transactional(readOnly = true)\npublic class DepartmentService {\n    @Autowired\n    private DepartmentRepository departmentRepository;\n\n    \/\/ \u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\n    public List&lt;String&gt; getEmployeeNames(Long departmentId) {\n        Department dept = departmentRepository.findById(departmentId).orElseThrow();\n        \/\/ \u30c8\u30e9\u30f3\u30b6\u30af\u30b7\u30e7\u30f3\u304c\u7d42\u4e86\u3057\u305f\u5f8c\u306bLazy\u306a\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306b\u30a2\u30af\u30bb\u30b9\n        return dept.getEmployees().stream()  \/\/ \u3053\u3053\u3067\u4f8b\u5916\u304c\u767a\u751f\n            .map(Employee::getName)\n            .collect(Collectors.toList());\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-54\">\u89e3\u6c7a\u65b9\u6cd51: JOIN FETCH \u306e\u4f7f\u7528<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Repository\npublic interface DepartmentRepository extends JpaRepository&lt;Department, Long&gt; {\n    @Query(\"SELECT d FROM Department d LEFT JOIN FETCH d.employees WHERE d.id = :id\")\n    Optional&lt;Department&gt; findByIdWithEmployees(@Param(\"id\") Long id);\n}\n\n@Service\n@Transactional(readOnly = true)\npublic class DepartmentService {\n    public List&lt;String&gt; getEmployeeNames(Long departmentId) {\n        Department dept = departmentRepository\n            .findByIdWithEmployees(departmentId)\n            .orElseThrow();\n        \/\/ \u4e8b\u524d\u306b\u30ed\u30fc\u30c9\u3055\u308c\u3066\u3044\u308b\u306e\u3067\u4f8b\u5916\u306f\u767a\u751f\u3057\u306a\u3044\n        return dept.getEmployees().stream()\n            .map(Employee::getName)\n            .collect(Collectors.toList());\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-55\">\u89e3\u6c7a\u65b9\u6cd52: @Transactional\u306e\u9069\u5207\u306a\u8a2d\u5b9a<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Service\npublic class DepartmentService {\n    @Transactional(readOnly = true)\n    public List&lt;String&gt; getEmployeeNames(Long departmentId) {\n        Department dept = departmentRepository.findById(departmentId).orElseThrow();\n        \/\/ \u30c8\u30e9\u30f3\u30b6\u30af\u30b7\u30e7\u30f3\u5185\u3067\u30a2\u30af\u30bb\u30b9\u3059\u308b\u306e\u3067\u4f8b\u5916\u306f\u767a\u751f\u3057\u306a\u3044\n        return dept.getEmployees().stream()\n            .map(Employee::getName)\n            .collect(Collectors.toList());\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-56\">\u89e3\u6c7a\u65b9\u6cd53: DTO\u306e\u6d3b\u7528<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Data\npublic class DepartmentDTO {\n    private Long id;\n    private String name;\n    private List&lt;String&gt; employeeNames;\n\n    public static DepartmentDTO from(Department department) {\n        DepartmentDTO dto = new DepartmentDTO();\n        dto.setId(department.getId());\n        dto.setName(department.getName());\n        \/\/ \u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u5185\u3067\u5fc5\u8981\u306a\u30c7\u30fc\u30bf\u3092\u53d6\u5f97\n        dto.setEmployeeNames(department.getEmployees().stream()\n            .map(Employee::getName)\n            .collect(Collectors.toList()));\n        return dto;\n    }\n}<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-57\">\u30c7\u30c3\u30c9\u30ed\u30c3\u30af\u56de\u907f\u306e\u305f\u3081\u306e\u30ed\u30c3\u30af\u6226\u7565<\/h2>\n\n\n\n<p>\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306e\u30c7\u30c3\u30c9\u30ed\u30c3\u30af\u306f\u3001\u8907\u6570\u306e\u30c8\u30e9\u30f3\u30b6\u30af\u30b7\u30e7\u30f3\u304c\u4e92\u3044\u306e\u30ed\u30c3\u30af\u3092\u5f85\u3061\u5408\u3046\u72b6\u614b\u3067\u767a\u751f\u3057\u307e\u3059\u3002\u9069\u5207\u306a\u30ed\u30c3\u30af\u6226\u7565\u3092\u5b9f\u88c5\u3059\u308b\u3053\u3068\u3067\u3001\u3053\u306e\u554f\u984c\u3092\u56de\u907f\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-58\">\u697d\u89b3\u7684\u30ed\u30c3\u30af\u306e\u5b9f\u88c5<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Entity\npublic class Inventory {\n    @Id\n    private Long id;\n\n    private Integer quantity;\n\n    @Version\n    private Long version;\n\n    public void decrementQuantity(int amount) {\n        if (quantity &lt; amount) {\n            throw new InsufficientInventoryException();\n        }\n        quantity -= amount;\n    }\n}\n\n@Service\npublic class InventoryService {\n    @Transactional(rollbackFor = OptimisticLockException.class)\n    public void updateInventory(Long id, int amount) {\n        try {\n            Inventory inventory = repository.findById(id).orElseThrow();\n            inventory.decrementQuantity(amount);\n            repository.save(inventory);\n        } catch (OptimisticLockException e) {\n            \/\/ \u30ea\u30c8\u30e9\u30a4\u30ed\u30b8\u30c3\u30af\u3092\u5b9f\u88c5\n            handleOptimisticLockException(id, amount);\n        }\n    }\n\n    private void handleOptimisticLockException(Long id, int amount) {\n        int retryCount = 0;\n        while (retryCount &lt; MAX_RETRY) {\n            try {\n                Thread.sleep(100 * (retryCount + 1));\n                updateInventory(id, amount);\n                return;\n            } catch (OptimisticLockException | InterruptedException e) {\n                retryCount++;\n            }\n        }\n        throw new ServiceException(\"Failed to update inventory after retries\");\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-59\">\u60b2\u89b3\u7684\u30ed\u30c3\u30af\u306e\u5b9f\u88c5<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Repository\npublic interface InventoryRepository extends JpaRepository&lt;Inventory, Long&gt; {\n    @Lock(LockModeType.PESSIMISTIC_WRITE)\n    @Query(\"SELECT i FROM Inventory i WHERE i.id = :id\")\n    Optional&lt;Inventory&gt; findByIdWithLock(@Param(\"id\") Long id);\n}\n\n@Service\npublic class InventoryService {\n    @Transactional\n    public void updateInventoryWithLock(Long id, int amount) {\n        Inventory inventory = repository\n            .findByIdWithLock(id)\n            .orElseThrow();\n        inventory.decrementQuantity(amount);\n        repository.save(inventory);\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-60\">\u30c7\u30c3\u30c9\u30ed\u30c3\u30af\u9632\u6b62\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u30c8\u30e9\u30f3\u30b6\u30af\u30b7\u30e7\u30f3\u9806\u5e8f\u306e\u7d71\u4e00<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Service\npublic class OrderService {\n    @Transactional\n    public void processOrder(Order order) {\n        \/\/ \u5e38\u306b\u5c0f\u3055\u3044ID\u304b\u3089\u51e6\u7406\n        List&lt;Long&gt; productIds = order.getItems().stream()\n            .map(item -&gt; item.getProduct().getId())\n            .sorted()\n            .collect(Collectors.toList());\n\n        for (Long productId : productIds) {\n            updateInventory(productId);\n        }\n    }\n}<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li><strong>\u30bf\u30a4\u30e0\u30a2\u30a6\u30c8\u8a2d\u5b9a<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Transactional(timeout = 5)\npublic void processOrderWithTimeout(Order order) {\n    \/\/ 5\u79d2\u3067\u30bf\u30a4\u30e0\u30a2\u30a6\u30c8\n    processOrder(order);\n}<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li><strong>\u30d0\u30c3\u30c1\u30b5\u30a4\u30ba\u306e\u6700\u9069\u5316<\/strong><\/li>\n<\/ol>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Service\npublic class BatchProcessingService {\n    private static final int BATCH_SIZE = 50;\n\n    @Transactional\n    public void processBatch(List&lt;Order&gt; orders) {\n        for (int i = 0; i &lt; orders.size(); i += BATCH_SIZE) {\n            List&lt;Order&gt; batch = orders.subList(\n                i, \n                Math.min(i + BATCH_SIZE, orders.size())\n            );\n            processOrderBatch(batch);\n            entityManager.flush();\n            entityManager.clear();\n        }\n    }\n}<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u5bfe\u7b56\u3092\u9069\u5207\u306b\u5b9f\u88c5\u3059\u308b\u3053\u3068\u3067\u3001\u591a\u304f\u306e\u4e00\u822c\u7684\u306aJPA\u306e\u554f\u984c\u3092\u56de\u907f\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3053\u308c\u3089\u306e\u77e5\u8b58\u3092\u6d3b\u7528\u3057\u305f\u5177\u4f53\u7684\u306a\u5b9f\u88c5\u4f8b\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\" id=\"i-61\">JPA\u3092\u4f7f\u7528\u3057\u305f\u5b9f\u88c5\u4f8b\u3068\u89e3\u8aac<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-62\">EC \u30b5\u30a4\u30c8\u306e\u5546\u54c1\u7ba1\u7406\u30b7\u30b9\u30c6\u30e0\u5b9f\u88c5\u4f8b<\/h2>\n\n\n\n<p>EC\u30b5\u30a4\u30c8\u306e\u5546\u54c1\u7ba1\u7406\u30b7\u30b9\u30c6\u30e0\u3067\u306f\u3001\u5546\u54c1\u3001\u30ab\u30c6\u30b4\u30ea\u3001\u5728\u5eab\u3001\u4fa1\u683c\u5c65\u6b74\u306a\u3069\u3001\u8907\u6570\u306e\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u9593\u306e\u95a2\u4fc2\u3092\u9069\u5207\u306b\u7ba1\u7406\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-63\">\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u8a2d\u8a08<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Entity\n@Table(name = \"products\")\npublic class Product extends BaseEntity {\n    @Id\n    @GeneratedValue(strategy = GenerationType.IDENTITY)\n    private Long id;\n\n    @Column(nullable = false)\n    private String name;\n\n    @Column(length = 2000)\n    private String description;\n\n    @ManyToOne(fetch = FetchType.LAZY)\n    @JoinColumn(name = \"category_id\")\n    private Category category;\n\n    @OneToMany(mappedBy = \"product\", cascade = CascadeType.ALL, orphanRemoval = true)\n    private List&lt;ProductPrice&gt; priceHistory = new ArrayList&lt;&gt;();\n\n    @OneToOne(mappedBy = \"product\", cascade = CascadeType.ALL)\n    private ProductInventory inventory;\n\n    @ElementCollection\n    @CollectionTable(name = \"product_images\")\n    private List&lt;String&gt; imageUrls = new ArrayList&lt;&gt;();\n}\n\n@Entity\n@Table(name = \"product_prices\")\npublic class ProductPrice {\n    @Id\n    @GeneratedValue(strategy = GenerationType.IDENTITY)\n    private Long id;\n\n    @ManyToOne\n    @JoinColumn(name = \"product_id\")\n    private Product product;\n\n    @Column(nullable = false)\n    private BigDecimal price;\n\n    @Column(nullable = false)\n    private LocalDateTime effectiveFrom;\n\n    private LocalDateTime effectiveTo;\n}\n\n@Entity\n@Table(name = \"product_inventory\")\npublic class ProductInventory {\n    @Id\n    @GeneratedValue(strategy = GenerationType.IDENTITY)\n    private Long id;\n\n    @OneToOne\n    @JoinColumn(name = \"product_id\")\n    private Product product;\n\n    private Integer quantity;\n\n    @Version\n    private Long version;\n\n    @ElementCollection\n    @CollectionTable(name = \"inventory_locations\")\n    private Map&lt;String, Integer&gt; locationQuantities = new HashMap&lt;&gt;();\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-64\">\u30ea\u30dd\u30b8\u30c8\u30ea\u5b9f\u88c5<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Repository\npublic interface ProductRepository extends JpaRepository&lt;Product, Long&gt; {\n    @Query(\"SELECT p FROM Product p LEFT JOIN FETCH p.category \" +\n           \"WHERE p.category.id = :categoryId\")\n    List&lt;Product&gt; findByCategoryWithDetails(@Param(\"categoryId\") Long categoryId);\n\n    @Query(\"SELECT DISTINCT p FROM Product p \" +\n           \"LEFT JOIN FETCH p.priceHistory ph \" +\n           \"WHERE ph.effectiveFrom &lt;= :date \" +\n           \"AND (ph.effectiveTo IS NULL OR ph.effectiveTo &gt; :date)\")\n    List&lt;Product&gt; findWithCurrentPrices(@Param(\"date\") LocalDateTime date);\n}\n\n@Repository\npublic interface ProductInventoryRepository extends JpaRepository&lt;ProductInventory, Long&gt; {\n    @Lock(LockModeType.PESSIMISTIC_WRITE)\n    @Query(\"SELECT pi FROM ProductInventory pi WHERE pi.product.id = :productId\")\n    Optional&lt;ProductInventory&gt; findByProductIdWithLock(@Param(\"productId\") Long productId);\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-65\">\u30b5\u30fc\u30d3\u30b9\u5c64\u306e\u5b9f\u88c5<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Service\n@Transactional\npublic class ProductService {\n    @Autowired\n    private ProductRepository productRepository;\n\n    @Autowired\n    private ProductInventoryRepository inventoryRepository;\n\n    public void updatePrice(Long productId, BigDecimal newPrice) {\n        Product product = productRepository.findById(productId)\n            .orElseThrow(() -&gt; new ProductNotFoundException(productId));\n\n        ProductPrice currentPrice = product.getPriceHistory().stream()\n            .filter(pp -&gt; pp.getEffectiveTo() == null)\n            .findFirst()\n            .orElseThrow(() -&gt; new PriceNotFoundException(productId));\n\n        currentPrice.setEffectiveTo(LocalDateTime.now());\n\n        ProductPrice newPriceEntity = new ProductPrice();\n        newPriceEntity.setProduct(product);\n        newPriceEntity.setPrice(newPrice);\n        newPriceEntity.setEffectiveFrom(LocalDateTime.now());\n\n        product.getPriceHistory().add(newPriceEntity);\n        productRepository.save(product);\n    }\n\n    public void updateInventory(Long productId, int quantity) {\n        ProductInventory inventory = inventoryRepository\n            .findByProductIdWithLock(productId)\n            .orElseThrow(() -&gt; new InventoryNotFoundException(productId));\n\n        if (inventory.getQuantity() + quantity &lt; 0) {\n            throw new InsufficientInventoryException(productId);\n        }\n\n        inventory.setQuantity(inventory.getQuantity() + quantity);\n        inventoryRepository.save(inventory);\n    }\n}<\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"i-66\">\u30bd\u30fc\u30b7\u30e3\u30eb\u30e1\u30c7\u30a3\u30a2\u306e\u30bf\u30a4\u30e0\u30e9\u30a4\u30f3\u5b9f\u88c5\u4f8b<\/h2>\n\n\n\n<p>\u30bd\u30fc\u30b7\u30e3\u30eb\u30e1\u30c7\u30a3\u30a2\u306e\u30bf\u30a4\u30e0\u30e9\u30a4\u30f3\u6a5f\u80fd\u3067\u306f\u3001\u6295\u7a3f\u3001\u30b3\u30e1\u30f3\u30c8\u3001\u3044\u3044\u306d\u306a\u3069\u306e\u95a2\u9023\u30c7\u30fc\u30bf\u3092\u52b9\u7387\u7684\u306b\u7ba1\u7406\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-67\">\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u8a2d\u8a08<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Entity\n@Table(name = \"posts\")\npublic class Post extends BaseEntity {\n    @Id\n    @GeneratedValue(strategy = GenerationType.IDENTITY)\n    private Long id;\n\n    @ManyToOne(fetch = FetchType.LAZY)\n    @JoinColumn(name = \"user_id\")\n    private User author;\n\n    @Column(nullable = false, length = 1000)\n    private String content;\n\n    @OneToMany(mappedBy = \"post\", cascade = CascadeType.ALL)\n    private List&lt;Comment&gt; comments = new ArrayList&lt;&gt;();\n\n    @OneToMany(mappedBy = \"post\", cascade = CascadeType.ALL)\n    private Set&lt;Like&gt; likes = new HashSet&lt;&gt;();\n\n    @ElementCollection\n    @CollectionTable(name = \"post_media\")\n    private List&lt;String&gt; mediaUrls = new ArrayList&lt;&gt;();\n}\n\n@Entity\n@Table(name = \"comments\")\npublic class Comment extends BaseEntity {\n    @Id\n    @GeneratedValue(strategy = GenerationType.IDENTITY)\n    private Long id;\n\n    @ManyToOne(fetch = FetchType.LAZY)\n    @JoinColumn(name = \"post_id\")\n    private Post post;\n\n    @ManyToOne(fetch = FetchType.LAZY)\n    @JoinColumn(name = \"user_id\")\n    private User author;\n\n    @Column(nullable = false, length = 500)\n    private String content;\n\n    @ManyToOne(fetch = FetchType.LAZY)\n    @JoinColumn(name = \"parent_id\")\n    private Comment parentComment;\n\n    @OneToMany(mappedBy = \"parentComment\")\n    private List&lt;Comment&gt; replies = new ArrayList&lt;&gt;();\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-68\">\u30ea\u30dd\u30b8\u30c8\u30ea\u3068\u30af\u30a8\u30ea\u306e\u6700\u9069\u5316<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Repository\npublic interface PostRepository extends JpaRepository&lt;Post, Long&gt; {\n    @Query(\"SELECT DISTINCT p FROM Post p \" +\n           \"LEFT JOIN FETCH p.author \" +\n           \"LEFT JOIN FETCH p.likes \" +\n           \"WHERE p.author.id IN \" +\n           \"(SELECT f.followed.id FROM Follow f WHERE f.follower.id = :userId) \" +\n           \"OR p.author.id = :userId \" +\n           \"ORDER BY p.createdAt DESC\")\n    Page&lt;Post&gt; findTimelineForUser(\n        @Param(\"userId\") Long userId, \n        Pageable pageable\n    );\n\n    @Query(\"SELECT p FROM Post p \" +\n           \"LEFT JOIN FETCH p.author \" +\n           \"LEFT JOIN FETCH p.comments c \" +\n           \"LEFT JOIN FETCH c.author \" +\n           \"WHERE p.id = :postId\")\n    Optional&lt;Post&gt; findByIdWithDetails(@Param(\"postId\") Long postId);\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-69\">\u30b5\u30fc\u30d3\u30b9\u5c64\u306e\u5b9f\u88c5<\/h3>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Service\n@Transactional\npublic class TimelineService {\n    @Autowired\n    private PostRepository postRepository;\n\n    @Autowired\n    private CommentRepository commentRepository;\n\n    @Cacheable(value = \"timeline\", key = \"#userId + '_' + #pageable.pageNumber\")\n    public Page&lt;PostDTO&gt; getTimeline(Long userId, Pageable pageable) {\n        return postRepository.findTimelineForUser(userId, pageable)\n            .map(this::convertToDTO);\n    }\n\n    @Transactional\n    public CommentDTO addComment(Long postId, Long userId, String content) {\n        Post post = postRepository.findById(postId)\n            .orElseThrow(() -&gt; new PostNotFoundException(postId));\n\n        Comment comment = new Comment();\n        comment.setPost(post);\n        comment.setAuthor(userRepository.getReferenceById(userId));\n        comment.setContent(content);\n\n        post.getComments().add(comment);\n        commentRepository.save(comment);\n\n        return convertToDTO(comment);\n    }\n\n    private PostDTO convertToDTO(Post post) {\n        return PostDTO.builder()\n            .id(post.getId())\n            .content(post.getContent())\n            .authorName(post.getAuthor().getName())\n            .likeCount(post.getLikes().size())\n            .commentCount(post.getComments().size())\n            .mediaUrls(post.getMediaUrls())\n            .createdAt(post.getCreatedAt())\n            .build();\n    }\n}<\/pre>\n\n\n\n<p>\u3053\u308c\u3089\u306e\u5b9f\u88c5\u4f8b\u306f\u3001JPA\u306e\u4e3b\u8981\u306a\u6a5f\u80fd\u3068\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af\u3092\u5b9f\u8df5\u7684\u306b\u793a\u3057\u3066\u3044\u307e\u3059\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u95a2\u9023\u306e\u9069\u5207\u306a\u8a2d\u8a08<\/strong><\/li>\n<\/ol>\n\n\n\n<ul 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