{"id":63,"date":"2026-04-05T18:03:13","date_gmt":"2026-04-05T18:03:13","guid":{"rendered":"https:\/\/www.we-notes.com\/ja\/er-diagram-relations-keys-cardinality-guide\/"},"modified":"2026-04-05T18:03:13","modified_gmt":"2026-04-05T18:03:13","slug":"er-diagram-relations-keys-cardinality-guide","status":"publish","type":"post","link":"https:\/\/www.we-notes.com\/ja\/er-diagram-relations-keys-cardinality-guide\/","title":{"rendered":"Q&amp;A\uff1aER\u56f3\u306b\u304a\u3051\u308b\u95a2\u4fc2\u3001\u30ad\u30fc\u3001\u304a\u3088\u3073\u57fa\u6570\u306b\u95a2\u3059\u308b\u6700\u3082\u4e00\u822c\u7684\u306a15\u306e\u6df7\u4e71\u3092\u89e3\u6d88\u3059\u308b"},"content":{"rendered":"<p>\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u95a2\u4fc2\u56f3\uff08ERD\uff09\u306f\u3001\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3\u306e\u8a2d\u8a08\u56f3\u3068\u3057\u3066\u6a5f\u80fd\u3057\u307e\u3059\u3002\u3057\u304b\u3057\u3001\u7d4c\u9a13\u8c4a\u5bcc\u306a\u30c7\u30b6\u30a4\u30ca\u30fc\u3067\u3059\u3089\u3001\u30d3\u30b8\u30cd\u30b9\u30ed\u30b8\u30c3\u30af\u3092\u30c7\u30fc\u30bf\u30e2\u30c7\u30eb\u306b\u5909\u63db\u3059\u308b\u969b\u306b\u56f0\u96e3\u3092\u62b1\u3048\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002\u305d\u306e\u66d6\u6627\u3055\u306e\u591a\u304f\u306f\u3001\u7528\u8a9e\u306e\u91cd\u8907\u3084\u69cb\u9020\u8981\u7d20\u9593\u306e\u5fae\u7d30\u306a\u9055\u3044\u306b\u8d77\u56e0\u3057\u307e\u3059\u3002\u3053\u306e\u30ac\u30a4\u30c9\u3067\u306f\u3001\u30ad\u30fc\u3001\u57fa\u6570\u3001\u95a2\u4fc2\u306b\u95a2\u3059\u308b\u6700\u3082\u6839\u5f37\u3044\u7591\u554f\u306b\u53d6\u308a\u7d44\u307f\u307e\u3059\u3002<\/p>\n<p>\u3053\u308c\u3089\u306e\u6982\u5ff5\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u3067\u3001\u30c7\u30fc\u30bf\u306e\u91cd\u8907\u3092\u9632\u304e\u3001\u30af\u30a8\u30ea\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u78ba\u4fdd\u3067\u304d\u307e\u3059\u300215\u306e\u5177\u4f53\u7684\u306a\u6df7\u4e71\u70b9\u3092\u9806\u306b\u89e3\u8aac\u3057\u3001\u660e\u78ba\u3067\u5b9f\u884c\u53ef\u80fd\u306a\u5b9a\u7fa9\u306b\u5206\u89e3\u3057\u307e\u3059\u3002\u5404\u30bb\u30af\u30b7\u30e7\u30f3\u306b\u306f\u5b9f\u969b\u306e\u4f8b\u3068\u8996\u899a\u7684\u306a\u8aac\u660e\u304c\u542b\u307e\u308c\u3066\u304a\u308a\u3001\u80cc\u5f8c\u306b\u3042\u308b\u30e1\u30ab\u30cb\u30ba\u30e0\u3092\u660e\u78ba\u306b\u3057\u307e\u3059\u3002<\/p>\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter\"><img alt=\"Chalkboard-style educational infographic explaining 15 key ER diagram concepts including entities, attributes, primary keys, foreign keys, one-to-one, one-to-many, many-to-many relationships, cardinality, modality, weak entities, composite keys, normalization, and notation styles, designed with hand-written teacher aesthetic for database design learning\" decoding=\"async\" src=\"https:\/\/www.we-notes.com\/wp-content\/uploads\/2026\/04\/er-diagram-15-concepts-chalkboard-infographic.jpg\"\/><\/figure>\n<\/div>\n<h2>1. \u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u3068\u5c5e\u6027\u306e\u9055\u3044\u306f\u4f55\u3067\u3059\u304b\uff1f \ud83c\udff7\ufe0f<\/h2>\n<p>\u3042\u308b<strong>\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3<\/strong>\u306f\u3001\u30c7\u30fc\u30bf\u304c\u683c\u7d0d\u3055\u308c\u308b\u5bfe\u8c61\u3068\u306a\u308b\u73fe\u5b9f\u4e16\u754c\u306e\u7269\u4f53\u307e\u305f\u306f\u6982\u5ff5\u3092\u8868\u3057\u307e\u3059\u3002\u901a\u5e38\u3001\u9577\u65b9\u5f62\u3067\u8868\u73fe\u3055\u308c\u307e\u3059\u3002\u4f8b\u3068\u3057\u3066<em>\u9867\u5ba2<\/em>, <em>\u88fd\u54c1<\/em>\u3001\u307e\u305f\u306f<em>\u6ce8\u6587<\/em>.<\/p>\n<p>\u3042\u308b<strong>\u5c5e\u6027<\/strong>\u306f\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306e\u6027\u8cea\u3092\u8868\u3057\u307e\u3059\u3002\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306b\u63a5\u7d9a\u3055\u308c\u305f\u6955\u5186\u3067\u8868\u73fe\u3055\u308c\u307e\u3059\u3002\u305f\u3068\u3048\u3070\u3001<em>\u9867\u5ba2\u540d<\/em>\u3001\u307e\u305f\u306f<em>\u88fd\u54c1\u4fa1\u683c<\/em>\u306f\u3001\u4e0a\u8a18\u306e\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306e\u5c5e\u6027\u3067\u3059\u3002<\/p>\n<ul>\n<li><strong>\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\uff1a<\/strong> \u540d\u8a5e\uff08\u8ab0\uff0f\u4f55\uff09\u3002<\/li>\n<li><strong> \u5c5e\u6027\uff1a<\/strong> \u5f62\u5bb9\u8a5e\uff08\u4f55\u3092\u8aac\u660e\u3059\u308b\u304b\uff09\u3002<\/li>\n<\/ul>\n<p>\u5c5e\u6027\u306b\u8907\u6570\u306e\u60c5\u5831\u304c\u542b\u307e\u308c\u308b\u5834\u5408\u3001\u6df7\u4e71\u304c\u751f\u3058\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002\u3082\u3057<em>\u4f4f\u6240<\/em>\u304c\u5c5e\u6027\u3067\u3042\u308b\u5834\u5408\u3001\u305d\u308c\u3092<em>\u901a\u308a\u540d<\/em>, <em>\u90fd\u5e02<\/em>\u3001\u304a\u3088\u3073 <em>Zip<\/em>\u3088\u308a\u826f\u3044\u6b63\u898f\u5316\u306e\u305f\u3081\u3002<\/p>\n<h2>2. \u4e3b\u30ad\u30fc\u3068\u4e00\u610f\u30ad\u30fc\u306e\u9055\u3044\u306f\u4f55\u3067\u3059\u304b\uff1f \ud83d\udd11<\/h2>\n<p>\u4e21\u65b9\u3068\u3082\u30c7\u30fc\u30bf\u306e\u6574\u5408\u6027\u3092\u4fdd\u8a3c\u3057\u307e\u3059\u304c\u3001\u4f7f\u7528\u65b9\u6cd5\u306f\u7570\u306a\u308a\u307e\u3059\u3002<\/p>\n<ul>\n<li><strong>\u4e3b\u30ad\u30fc\uff1a<\/strong> \u30c6\u30fc\u30d6\u30eb\u5185\u306e\u3059\u3079\u3066\u306e\u884c\u3092\u4e00\u610f\u306b\u8b58\u5225\u3057\u307e\u3059\u3002\u30c6\u30fc\u30d6\u30eb\u306b\u306f\u4e3b\u30ad\u30fc\u304c1\u3064\u3057\u304b\u3042\u308a\u307e\u305b\u3093\u3002null\u5024\u3092\u542b\u3081\u308b\u3053\u3068\u306f\u3067\u304d\u307e\u305b\u3093\u3002<\/li>\n<li><strong>\u4e00\u610f\u30ad\u30fc\uff1a<\/strong> \u5217\u5185\u306e\u3059\u3079\u3066\u306e\u5024\u304c\u7570\u306a\u308b\u3053\u3068\u3092\u4fdd\u8a3c\u3057\u307e\u3059\u3002\u30c6\u30fc\u30d6\u30eb\u306b\u306f\u8907\u6570\u306e\u4e00\u610f\u30ad\u30fc\u3092\u6301\u3064\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002null\u5024\u306f\u3057\u3070\u3057\u3070\u8a31\u53ef\u3055\u308c\u307e\u3059\uff08\u5b9f\u88c5\u306b\u3088\u3063\u3066\u7570\u306a\u308a\u307e\u3059\uff09\u3002<\/li>\n<\/ul>\n<p>\u4e3b\u30ad\u30fc\u3092\u30ec\u30b3\u30fc\u30c9\u306e\u793e\u4f1a\u4fdd\u969c\u756a\u53f7\u3068\u8003\u3048\u3066\u304f\u3060\u3055\u3044\u3002\u4e00\u610f\u30ad\u30fc\u306f\u30d1\u30b9\u30dd\u30fc\u30c8\u756a\u53f7\u306e\u3088\u3046\u306a\u3082\u306e\u3067\u3001\u3084\u306f\u308a\u4e00\u610f\u3067\u3059\u304c\u3001\u500b\u4eba\u306b\u5bfe\u3057\u3066\u8907\u6570\u306e\u56fa\u6709\u8b58\u5225\u5b50\u304c\u5b58\u5728\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<h2>3. \u5916\u90e8\u30ad\u30fc\u3068\u306f\u4f55\u304b\u3001\u305d\u3057\u3066\u30c6\u30fc\u30d6\u30eb\u3092\u3069\u306e\u3088\u3046\u306b\u30ea\u30f3\u30af\u3059\u308b\u306e\u304b\uff1f \ud83d\udd17<\/h2>\n<p>A <strong>\u5916\u90e8\u30ad\u30fc<\/strong> \u306f\u3001\u3042\u308b\u30c6\u30fc\u30d6\u30eb\u5185\u306e\u30d5\u30a3\u30fc\u30eb\u30c9\uff08\u307e\u305f\u306f\u8907\u6570\u306e\u30d5\u30a3\u30fc\u30eb\u30c9\u306e\u96c6\u5408\uff09\u3067\u3001\u5225\u306e\u30c6\u30fc\u30d6\u30eb\u306e\u4e3b\u30ad\u30fc\u3092\u53c2\u7167\u3057\u307e\u3059\u3002\u3053\u308c\u306b\u3088\u308a\u30012\u3064\u306e\u30c6\u30fc\u30d6\u30eb\u306e\u9593\u306b\u30ea\u30f3\u30af\u304c\u78ba\u7acb\u3055\u308c\u307e\u3059\u3002<\/p>\n<p>\u4ee5\u4e0b\u306e\u3088\u3046\u306a <em>\u6ce8\u6587<\/em> \u30c6\u30fc\u30d6\u30eb\u3092\u8003\u3048\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u3069\u306e <em>\u9867\u5ba2<\/em> \u304c\u6ce8\u6587\u3092\u3057\u305f\u304b\u3092\u628a\u63e1\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<em>\u9867\u5ba2ID<\/em> \u30c6\u30fc\u30d6\u30eb\u5185\u306e <em>\u6ce8\u6587<\/em> \u306f\u5916\u90e8\u30ad\u30fc\u3067\u3059\u3002<\/p>\n<table>\n<thead>\n<tr>\n<th>\u30c6\u30fc\u30d6\u30eb<\/th>\n<th>\u5217<\/th>\n<th>\u5f79\u5272<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\u9867\u5ba2<\/td>\n<td>\u9867\u5ba2ID<\/td>\n<td>\u4e3b\u30ad\u30fc<\/td>\n<\/tr>\n<tr>\n<td>\u6ce8\u6587<\/td>\n<td>\u9867\u5ba2ID<\/td>\n<td>\u5916\u90e8\u30ad\u30fc<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u3053\u306e\u95a2\u4fc2\u306b\u3088\u308a\u3001\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306f\u53c2\u7167\u6574\u5408\u6027\u3092\u7dad\u6301\u3067\u304d\u3001\u6709\u52b9\u306a\u9867\u5ba2\u304c\u5b58\u5728\u3057\u306a\u3044\u6ce8\u6587\u306f\u5b58\u5728\u3057\u306a\u3044\u3053\u3068\u3092\u4fdd\u8a3c\u3057\u307e\u3059\u3002<\/p>\n<h2>4. \u95a2\u4fc2\u304c1\u5bfe1\u306b\u306a\u308b\u306e\u306f\u3044\u3064\u3067\u3059\u304b\uff1f \ud83e\udd1d<\/h2>\n<p>1\u5bfe1\uff081:1\uff09\u306e\u95a2\u4fc2\u3068\u306f\u3001Table A\u306e1\u3064\u306e\u30ec\u30b3\u30fc\u30c9\u304cTable B\u306e\u6b63\u78ba\u306b1\u3064\u306e\u30ec\u30b3\u30fc\u30c9\u306b\u95a2\u9023\u3057\u3001\u305d\u306e\u9006\u3082\u307e\u305f\u6210\u308a\u7acb\u3064\u5834\u5408\u3092\u6307\u3057\u307e\u3059\u3002<\/p>\n<ul>\n<li><strong>\u4f8b\uff1a<\/strong> A <em>Person<\/em> \u3068 <em>\u30d1\u30b9\u30dd\u30fc\u30c8<\/em>.<\/li>\n<li><strong>\u5b9f\u88c5\u65b9\u6cd5\uff1a<\/strong>\u901a\u5e38\u3001\u4e00\u65b9\u306e\u30c6\u30fc\u30d6\u30eb\u306e\u4e3b\u30ad\u30fc\u3092\u3082\u3046\u4e00\u65b9\u306e\u30c6\u30fc\u30d6\u30eb\u306e\u5916\u90e8\u30ad\u30fc\u3068\u3057\u3066\u914d\u7f6e\u3059\u308b\u3053\u3068\u3067\u5b9f\u88c5\u3055\u308c\u307e\u3059\u3002<\/li>\n<\/ul>\n<p>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3084\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u3092\u6700\u9069\u5316\u3059\u308b\u305f\u3081\u306b\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u3092\u5206\u5272\u3059\u308b\u5834\u5408\u306b\u3001\u3053\u306e\u65b9\u6cd5\u306f\u4e00\u822c\u7684\u3067\u3059\u3002\u305f\u3068\u3048\u3070\u3001<em>\u793e\u4f1a\u4fdd\u969c\u756a\u53f7<\/em>\u30921:1\u3067\u30ea\u30f3\u30af\u3055\u308c\u305f\u5225\u30c6\u30fc\u30d6\u30eb\u306b\u79fb\u52d5\u3059\u308b\u306a\u3069\u3067\u3059\u3002<\/p>\n<h2>5. 1\u5bfe\u591a\u306e\u95a2\u4fc2\u306f\u3069\u306e\u3088\u3046\u306b\u6a5f\u80fd\u3059\u308b\u306e\u3067\u3059\u304b\uff1f \ud83d\udce6<\/h2>\n<p>\u3053\u308c\u306f\u6700\u3082\u4e00\u822c\u7684\u306a\u95a2\u4fc2\u30bf\u30a4\u30d7\u3067\u3059\u3002Table A\u306e1\u3064\u306e\u30ec\u30b3\u30fc\u30c9\u304cTable B\u306e\u8907\u6570\u306e\u30ec\u30b3\u30fc\u30c9\u306b\u95a2\u9023\u3057\u307e\u3059\u304c\u3001Table B\u306e\u30ec\u30b3\u30fc\u30c9\u306fTable A\u306e1\u3064\u306e\u30ec\u30b3\u30fc\u30c9\u306b\u306e\u307f\u95a2\u9023\u3057\u307e\u3059\u3002<\/p>\n<ul>\n<li><strong>\u4f8b\uff1a<\/strong> <em>\u90e8\u9580<\/em> \u304b\u3089 <em>\u5f93\u696d\u54e1<\/em>.<\/li>\n<li><strong>\u65b9\u5411\uff1a<\/strong>1\u3064\u306e\u90e8\u9580\u306b\u306f\u8907\u6570\u306e\u5f93\u696d\u54e1\u304c\u6240\u5c5e\u3057\u307e\u3059\u3002<\/li>\n<\/ul>\n<p>ERD\u3067\u306f\u3001\u3053\u306e\u95a2\u4fc2\u306f2\u3064\u306e\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u3092\u7d50\u3076\u7dda\u3067\u63cf\u304b\u308c\u307e\u3059\u3002\u300c\u591a\u300d\u306e\u5074\u306b\u5916\u90e8\u30ad\u30fc\u304c\u914d\u7f6e\u3055\u308c\u307e\u3059\u3002<\/p>\n<h2>6. \u591a\u5bfe\u591a\u306e\u95a2\u4fc2\u306f\u306a\u305c\u554f\u984c\u306b\u306a\u308b\u306e\u3067\u3059\u304b\uff1f \u2696\ufe0f<\/h2>\n<p>\u8907\u6570\u306e\u30ec\u30b3\u30fc\u30c9\u304cTable A\u3068\u8907\u6570\u306e\u30ec\u30b3\u30fc\u30c9\u304cTable B\u306b\u95a2\u9023\u3059\u308b\u5834\u5408\u3001\u591a\u5bfe\u591a\uff08M:N\uff09\u306e\u95a2\u4fc2\u304c\u5b58\u5728\u3057\u307e\u3059\u3002\u30ea\u30ec\u30fc\u30b7\u30e7\u30ca\u30eb\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306b\u76f4\u63a5\u5b9f\u88c5\u3059\u308b\u306b\u306f\u3001\u30d6\u30ea\u30c3\u30b8\u304c\u5fc5\u8981\u3067\u3059\u3002<\/p>\n<ul>\n<li><strong>\u554f\u984c\u70b9\uff1a<\/strong>1\u3064\u306e\u884c\u306b\u8907\u6570\u306eID\u3092\u683c\u7d0d\u3059\u308b\u5fc5\u8981\u304c\u3042\u308b\u305f\u3081\u3001\u5358\u7d14\u306b1\u3064\u306e\u30c6\u30fc\u30d6\u30eb\u306b\u5916\u90e8\u30ad\u30fc\u3092\u8ffd\u52a0\u3059\u308b\u3053\u3068\u306f\u3067\u304d\u307e\u305b\u3093\u3002<\/li>\n<li><strong>\u89e3\u6c7a\u7b56\uff1a<\/strong> \u7d50\u5408\u30c6\u30fc\u30d6\u30eb\uff08\u95a2\u9023\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\uff09\u3092\u4f5c\u6210\u3059\u308b\u3002<\/li>\n<\/ul>\n<p>\u306b\u5bfe\u3057\u3066<em>\u5b66\u751f<\/em>\u304a\u3088\u3073<em>\u6388\u696d<\/em>\u306b\u5bfe\u3057\u3066\u3001<em>\u767b\u9332<\/em>\u30c6\u30fc\u30d6\u30eb\u3092\u4f5c\u6210\u3057\u3001<em>\u5b66\u751fID<\/em>\u304a\u3088\u3073<em>\u6388\u696dID<\/em>\u3053\u308c\u306b\u3088\u308a\u3001M:N\u95a2\u4fc2\u304c2\u3064\u306e1:Many\u95a2\u4fc2\u306b\u5909\u63db\u3055\u308c\u308b\u3002<\/p>\n<h2>7. \u30ab\u30fc\u30c7\u30a3\u30ca\u30ea\u30c6\u30a3\u3068\u30e2\u30c0\u30ea\u30c6\u30a3\u306e\u9055\u3044\u306f\u4f55\u3067\u3059\u304b\uff1f \u2696\ufe0f<\/h2>\n<p>\u3053\u308c\u3089\u306e\u7528\u8a9e\u306f\u95a2\u4fc2\u306e\u5236\u7d04\u3092\u8aac\u660e\u3057\u3066\u304a\u308a\u3001\u985e\u4f3c\u3057\u305f\u8868\u8a18\u306e\u305f\u3081\u6df7\u540c\u3055\u308c\u304c\u3061\u3067\u3042\u308b\u3002<\/p>\n<ul>\n<li><strong>\u30ab\u30fc\u30c7\u30a3\u30ca\u30ea\u30c6\u30a3\uff1a<\/strong> \u6700\u5927\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u6570\u3002\uff08\u4f8b\uff1a1\u5bfe\u591a\uff09<\/li>\n<li><strong>\u30e2\u30c0\u30ea\u30c6\u30a3\uff1a<\/strong> \u6700\u5c0f\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u6570\u3002\uff08\u4f8b\uff1a\u5fc5\u9808\u307e\u305f\u306f\u4efb\u610f\uff09<\/li>\n<\/ul>\n<p>\u4f8b\uff1a<em>\u5f93\u696d\u54e1<\/em>\u306f<em>\u90e8\u7f72<\/em>\u3092\u6301\u3063\u3066\u3044\u308b\u5fc5\u8981\u304c\u3042\u308b\uff08\u30e2\u30c0\u30ea\u30c6\u30a3\uff1a\u5fc5\u9808\/1\uff09\u3002<em>\u90e8\u7f72<\/em>\u306f<em>\u5f93\u696d\u54e1<\/em>\u304c\u3044\u306a\u304f\u3066\u3082\u5b58\u5728\u53ef\u80fd\u3067\u3042\u308b\uff08\u30e2\u30c0\u30ea\u30c6\u30a3\uff1a\u4efb\u610f\/0\uff09\u3002<\/p>\n<h2>8. \u8b58\u5225\u7684\u95a2\u4fc2\u3068\u975e\u8b58\u5225\u7684\u95a2\u4fc2 \ud83e\udde9<\/h2>\n<p>\u305d\u306e\u9055\u3044\u306f\u3001\u5b50\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306e\u4f9d\u5b58\u95a2\u4fc2\u306b\u306b\u3042\u308b\u3002<\/p>\n<ul>\n<li><strong>\u8b58\u5225\u95a2\u4fc2\uff1a<\/strong> \u5b50\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306f\u89aa\u306a\u3057\u3067\u306f\u5b58\u5728\u3067\u304d\u306a\u3044\u3002\u5916\u90e8\u30ad\u30fc\u306f\u5b50\u306e\u4e3b\u30ad\u30fc\u306e\u4e00\u90e8\u3067\u3042\u308b\u3002\u901a\u5e38\u3001\u5b9f\u7dda\u3067\u793a\u3055\u308c\u308b\u3002<\/li>\n<li><strong>\u975e\u8b58\u5225\u95a2\u4fc2\uff1a<\/strong> \u5b50\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306f\u72ec\u7acb\u3057\u3066\u5b58\u5728\u3067\u304d\u308b\u3002\u5916\u90e8\u30ad\u30fc\u306f\u4e3b\u30ad\u30fc\u306e\u4e00\u90e8\u3067\u306f\u306a\u3044\u3002\u901a\u5e38\u3001\u7834\u7dda\u3067\u793a\u3055\u308c\u308b\u3002<\/li>\n<\/ul>\n<p>\u6b21\u306e\u3088\u3046\u306a\u3082\u306e\u3092\u8003\u3048\u308b\uff1a<em>\u8acb\u6c42\u66f8<\/em>\uff08\u89aa\uff09\u3068<em>\u8acb\u6c42\u66f8\u660e\u7d30\u884c<\/em>\uff08\u5b50\uff09\u3002\u660e\u7d30\u884c\u306f\u8b58\u5225\u95a2\u4fc2\u3067\u3042\u308b\u3002\u660e\u7d30\u884c\u306f\u8acb\u6c42\u66f8\u304c\u306a\u3051\u308c\u3070\u610f\u5473\u3092\u6301\u305f\u306a\u3044\u304b\u3089\u3067\u3042\u308b\u3002<\/p>\n<h2>9. \u518d\u5e30\u7684\u95a2\u4fc2\u3068\u306f\u4f55\u304b\uff1f \ud83d\udd04<\/h2>\n<p>\u518d\u5e30\u7684\u95a2\u4fc2\u3068\u306f\u3001\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u304c\u81ea\u5206\u81ea\u8eab\u3068\u95a2\u4fc2\u3092\u6301\u3064\u3068\u304d\u306b\u767a\u751f\u3059\u308b\u3002\u3053\u308c\u306f\u968e\u5c64\u30c7\u30fc\u30bf\u3067\u3088\u304f\u898b\u3089\u308c\u308b\u3002<\/p>\n<ul>\n<li><strong>\u4f8b\uff1a<\/strong>\u3042\u308b<em>\u5f93\u696d\u54e1<\/em>\u30c6\u30fc\u30d6\u30eb\u3067\u30011\u4eba\u306e\u5f93\u696d\u54e1\u304c\u4ed6\u306e\u5f93\u696d\u54e1\u306e<em>\u30de\u30cd\u30fc\u30b8\u30e3\u30fc<\/em>\u3067\u3042\u308b\u3082\u306e\u3002<\/li>\n<li><strong>\u5b9f\u88c5\uff1a<\/strong> \u540c\u3058\u30c6\u30fc\u30d6\u30eb\u5185\u306e\u5916\u90e8\u30ad\u30fc\u3067\u3001\u540c\u3058\u30c6\u30fc\u30d6\u30eb\u306e\u4e3b\u30ad\u30fc\u3092\u6307\u3059\u3082\u306e\u3002<\/li>\n<\/ul>\n<p>\u3053\u306e\u69cb\u9020\u306f\u7d44\u7e54\u56f3\u3084\u30b5\u30d6\u30ab\u30c6\u30b4\u30ea\u3092\u6301\u3064\u88fd\u54c1\u30ab\u30c6\u30b4\u30ea\u3092\u30b5\u30dd\u30fc\u30c8\u3059\u308b\u3002<\/p>\n<h2>10. \u5f31\u3044\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u3068\u5f37\u3044\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306e\u9055\u3044\u306f\u4f55\u304b\uff1f \ud83c\udf31<\/h2>\n<p>\u3042\u308b<strong>\u5f37\u3044\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3<\/strong>\u306f\u3001\u4ed6\u306e\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306b\u4f9d\u5b58\u3057\u306a\u3044\u4e3b\u30ad\u30fc\u3092\u6301\u3064\u3002\u4e00\u65b9\u3001<strong>\u5f31\u3044\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3<\/strong>\u306f\u3001\u89aa\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306e\u4e3b\u30ad\u30fc\u306a\u3057\u3067\u306f\u4e00\u610f\u306b\u8b58\u5225\u3067\u304d\u306a\u3044\u3002<\/p>\n<ul>\n<li><strong>\u8996\u899a\u7684\u8868\u73fe\uff1a<\/strong>\u5f31\u3044\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306f\u3057\u3070\u3057\u3070\u4e8c\u91cd\u306e\u9577\u65b9\u5f62\u3067\u63cf\u304b\u308c\u308b\u3002<\/li>\n<li><strong>\u4f9d\u5b58\u95a2\u4fc2\uff1a<\/strong> \u3053\u308c\u3089\u306f\u8b58\u5225\u95a2\u4fc2\u306b\u4f9d\u5b58\u3057\u3066\u3044\u308b\u3002<\/li>\n<\/ul>\n<p>\u4f8b\uff1aA <em>\u5f93\u5c5e\u8005<\/em> \uff08\u914d\u5076\u8005\uff0f\u5b50\u4f9b\uff09\u3092\u4f1a\u793e\u306e\u30b7\u30b9\u30c6\u30e0\u5185\u3067\u3002\u5f93\u5c5e\u8005\u306e\u30ec\u30b3\u30fc\u30c9\u306f\u901a\u5e38\u3001\u72ec\u81ea\u306e\u56fa\u6709ID\u3092\u6301\u305f\u306a\u3044\u3002\u4ee3\u308f\u308a\u306b\u3001<em>EmployeeID<\/em> \u306b\u3088\u3063\u3066\u8b58\u5225\u3055\u308c\u308b\u3002<\/p>\n<h2>11. \u7d44\u307f\u5408\u308f\u305b\u30ad\u30fc\u3092\u4f7f\u7528\u3059\u3079\u304d\u30bf\u30a4\u30df\u30f3\u30b0\u306f\u3044\u3064\u3067\u3059\u304b\uff1f \ud83e\udde9<\/h2>\n<p>A <strong>\u7d44\u307f\u5408\u308f\u305b\u30ad\u30fc<\/strong> \u306f\u30012\u3064\u4ee5\u4e0a\u306e\u5217\u3092\u7d44\u307f\u5408\u308f\u305b\u30661\u884c\u3092\u4e00\u610f\u306b\u8b58\u5225\u3059\u308b\u3082\u306e\u3067\u3042\u308b\u3002\u5358\u4e00\u306e\u5217\u3067\u306f\u4e00\u610f\u6027\u304c\u78ba\u4fdd\u3067\u304d\u306a\u3044\u5834\u5408\u306b\u4f7f\u7528\u3055\u308c\u308b\u3002<\/p>\n<ul>\n<li><strong>\u30b7\u30ca\u30ea\u30aa\uff1a<\/strong> A <em>StudentCourse<\/em> \u30c6\u30fc\u30d6\u30eb\u3002<\/li>\n<li><strong>\u30ad\u30fc\uff1a<\/strong> <em>StudentID<\/em> + <em>CourseID<\/em>.<\/li>\n<\/ul>\n<p>\u3053\u306e\u6587\u8108\u3067\u306f\u3001\u3069\u3061\u3089\u306eID\u3082\u72ec\u81ea\u306b\u4e00\u610f\u3067\u306f\u306a\u3044\u304c\u3001\u7d44\u307f\u5408\u308f\u305b\u308b\u3068\u4e00\u610f\u306b\u306a\u308b\u3002\u7d44\u307f\u5408\u308f\u305b\u30ad\u30fc\u306f\u4ed6\u306e\u30c6\u30fc\u30d6\u30eb\u306e\u5916\u90e8\u30ad\u30fc\u95a2\u4fc2\u3092\u8907\u96d1\u306b\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\u305f\u3081\u3001\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3042\u308b\u3002<\/p>\n<h2>12. \u30b5\u30ed\u30b2\u30fc\u30c8\u30ad\u30fc vs. \u30ca\u30c1\u30e5\u30e9\u30eb\u30ad\u30fc\uff1a\u3069\u3061\u3089\u3092\u9078\u3076\u3079\u304d\u304b\uff1f \ud83d\udd22<\/h2>\n<p>\u3053\u308c\u306f\u6226\u7565\u7684\u306a\u8a2d\u8a08\u4e0a\u306e\u6c7a\u5b9a\u3067\u3042\u308b\u3002<\/p>\n<ul>\n<li><strong>\u30ca\u30c1\u30e5\u30e9\u30eb\u30ad\u30fc\uff1a<\/strong> \u5b9f\u4e16\u754c\u306e\u5c5e\u6027\uff08\u4f8b\uff1a\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u3001\u793e\u4f1a\u4fdd\u969c\u756a\u53f7\uff09\u3002\u5229\u70b9\uff1a\u610f\u5473\u306e\u3042\u308b\u3082\u306e\u3002\u6b20\u70b9\uff1a\u5909\u66f4\u3055\u308c\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\u3001\u9577\u304f\u306a\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\u3001\u307e\u305f\u306f\u6a5f\u5bc6\u60c5\u5831\u3092\u542b\u3080\u53ef\u80fd\u6027\u304c\u3042\u308b\u3002<\/li>\n<li><strong>\u30b5\u30ed\u30b2\u30fc\u30c8\u30ad\u30fc\uff1a<\/strong> \u30b7\u30b9\u30c6\u30e0\u304c\u751f\u6210\u3059\u308bID\uff08\u4f8b\uff1a\u81ea\u52d5\u5897\u5206\u6574\u6570\uff09\u3002\u5229\u70b9\uff1a\u5b89\u5b9a\u3057\u3066\u3044\u308b\u3001\u77ed\u3044\u3001\u9ad8\u901f\u3002\u6b20\u70b9\uff1a\u30d3\u30b8\u30cd\u30b9\u4e0a\u306e\u610f\u5473\u304c\u306a\u3044\u3002<\/li>\n<\/ul>\n<p>\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3067\u306f\u3001\u5185\u90e8\u30c6\u30fc\u30d6\u30eb\u69cb\u9020\u306b\u306f\u30b5\u30ed\u30b2\u30fc\u30c8\u30ad\u30fc\u3092\u597d\u3080\u50be\u5411\u304c\u3042\u308b\u4e00\u65b9\u3067\u3001\u30ca\u30c1\u30e5\u30e9\u30eb\u30ad\u30fc\u306f\u691c\u7d22\u3084\u30ec\u30dd\u30fc\u30c8\u4f5c\u6210\u306b\u304a\u3044\u3066\u4f9d\u7136\u3068\u3057\u3066\u6709\u7528\u3067\u3042\u308b\u3002<\/p>\n<h2>13. \u6b63\u898f\u5316\u306fERD\u306b\u3069\u306e\u3088\u3046\u306b\u5f71\u97ff\u3059\u308b\u304b\uff1f \ud83d\udcc9<\/h2>\n<p>\u6b63\u898f\u5316\u3068\u306f\u3001\u30c7\u30fc\u30bf\u306e\u91cd\u8907\u3092\u6e1b\u3089\u3059\u305f\u3081\u306b\u30c7\u30fc\u30bf\u3092\u6574\u7406\u3059\u308b\u30d7\u30ed\u30bb\u30b9\u3067\u3042\u308b\u3002\u6b63\u898f\u5316\u3059\u308b\u306b\u3064\u308c\u3066ERD\u3082\u9032\u5316\u3059\u308b\u3002<\/p>\n<ul>\n<li><strong>1NF\uff1a<\/strong>\u7e70\u308a\u8fd4\u3057\u30b0\u30eb\u30fc\u30d7\u3092\u6392\u9664\u3059\u308b\u3002<\/li>\n<li><strong>2NF:<\/strong>\u90e8\u5206\u7684\u4f9d\u5b58\u95a2\u4fc2\u3092\u524a\u9664\u3059\u308b\u3002<\/li>\n<li><strong>3NF:<\/strong>\u63a8\u79fb\u7684\u4f9d\u5b58\u95a2\u4fc2\u3092\u524a\u9664\u3059\u308b\u3002<\/li>\n<\/ul>\n<p>\u3088\u308a\u9ad8\u3044\u6b63\u898f\u5316\u306f\u901a\u5e38\u3001\u30c6\u30fc\u30d6\u30eb\u3068\u95a2\u4fc2\u306e\u6570\u3092\u5897\u52a0\u3055\u305b\u308b\u3002\u30c7\u30fc\u30bf\u6574\u5408\u6027\u3092\u5411\u4e0a\u3055\u305b\u308b\u4e00\u65b9\u3067\u3001\u30af\u30a8\u30ea\u3092\u8907\u96d1\u306b\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\u3002\u6b63\u898f\u5316\u306e\u30ec\u30d9\u30eb\u3068\u30af\u30a8\u30ea\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u30cb\u30fc\u30ba\u306e\u30d0\u30e9\u30f3\u30b9\u3092\u53d6\u308b\u5fc5\u8981\u304c\u3042\u308b\u3002<\/p>\n<h2>14. \u30af\u30ed\u30a6\u30ba\u30d5\u30c3\u30c8\u8a18\u6cd5 vs. \u30c1\u30a7\u30f3\u8a18\u6cd5\uff1a\u3069\u3061\u3089\u304c\u6a19\u6e96\u304b\uff1f \ud83d\udc63<\/h2>\n<p>\u8a18\u6cd5\u3068\u306f\u3001\u95a2\u4fc2\u304c\u8996\u899a\u7684\u306b\u3069\u306e\u3088\u3046\u306b\u8868\u73fe\u3055\u308c\u308b\u304b\u3092\u6307\u3059\u3002<\/p>\n<ul>\n<li><strong>\u30af\u30ed\u30a6\u30ba\u30d5\u30c3\u30c8\uff1a<\/strong>\u7dda\u306e\u7aef\u306b\u7dda\u3001\u5341\u5b57\u3001\u5186\u306a\u3069\u306e\u8a18\u53f7\u3092\u4f7f\u7528\u3059\u308b\u3002\u73fe\u4ee3\u306e\u30c4\u30fc\u30eb\u3067\u975e\u5e38\u306b\u4e00\u822c\u7684\u3067\u3042\u308b\u3002<\/li>\n<li><strong>\u30c1\u30a7\u30f3\uff1a<\/strong>\u95a2\u4fc2\u306b\u306f\u83f1\u5f62\u3001\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u306b\u306f\u9577\u65b9\u5f62\u3092\u4f7f\u7528\u3059\u308b\u3002\u3088\u308a\u5b66\u8853\u7684\u3067\u3042\u308b\u3002<\/li>\n<\/ul>\n<p>\u30af\u30ed\u30a6\u30ba\u30d5\u30c3\u30c8\u8a18\u6cd5\u306f\u3001\u5b9f\u88c5\u306b\u304a\u3044\u3066\u4e00\u822c\u7684\u306b\u597d\u307e\u308c\u308b\u3002\u305d\u308c\u306fSQL\u5236\u7d04\u306b\u3088\u308a\u76f4\u63a5\u7684\u306b\u5bfe\u5fdc\u3059\u308b\u305f\u3081\u3067\u3042\u308b\u3002\u3057\u304b\u3057\u3001\u30c1\u30a7\u30f3\u8a18\u6cd5\u306f\u9ad8\u30ec\u30d9\u30eb\u306e\u6982\u5ff5\u7684\u30e2\u30c7\u30ea\u30f3\u30b0\u306b\u975e\u5e38\u306b\u9069\u3057\u3066\u3044\u308b\u3002<\/p>\n<h2>15. ERD vs. \u30c7\u30fc\u30bf\u30d5\u30ed\u30fc\u30c0\u30a4\u30a2\u30b0\u30e9\u30e0\uff08DFD\uff09 \ud83d\udcca<\/h2>\n<p>\u3053\u308c\u3089\u306f\u30b7\u30b9\u30c6\u30e0\u8a2d\u8a08\u30e9\u30a4\u30d5\u30b5\u30a4\u30af\u30eb\u306b\u304a\u3044\u3066\u7570\u306a\u308b\u76ee\u7684\u3092\u679c\u305f\u3059\u3002<\/p>\n<ul>\n<li><strong>ERD\uff1a<\/strong>\u6ce8\u76ee\u3059\u308b\u70b9\u306f<em>\u30c7\u30fc\u30bf\u69cb\u9020<\/em>\u304a\u3088\u3073\u4fdd\u5b58\u3002\u95a2\u4fc2\u306e\u9759\u7684\u30d3\u30e5\u30fc\u3002<\/li>\n<li><strong>DFD\uff1a<\/strong>\u6ce8\u76ee\u3059\u308b\u70b9\u306f<em>\u30c7\u30fc\u30bf\u306e\u79fb\u52d5<\/em>\u304a\u3088\u3073\u30d7\u30ed\u30bb\u30b9\u3002\u30c7\u30fc\u30bf\u304c\u30b7\u30b9\u30c6\u30e0\u5185\u3067\u3069\u306e\u3088\u3046\u306b\u6d41\u308c\u3066\u3044\u308b\u304b\u306e\u52d5\u7684\u30d3\u30e5\u30fc\u3002<\/li>\n<\/ul>\n<p>\u3053\u308c\u3089\u3092\u6df7\u540c\u3057\u3066\u306f\u306a\u3089\u306a\u3044\u3002ERD\u306f\u3001\u3069\u306e\u3088\u3046\u306a\u30c7\u30fc\u30bf\u304c\u5b58\u5728\u3059\u308b\u304b\u3092\u6559\u3048\u3066\u304f\u308c\u308b\u3002DFD\u306f\u3001\u305d\u306e\u30c7\u30fc\u30bf\u304c\u3069\u306e\u3088\u3046\u306b\u51e6\u7406\u3055\u308c\u308b\u304b\u3092\u6559\u3048\u3066\u304f\u308c\u308b\u3002\u5b8c\u5168\u306a\u30b7\u30b9\u30c6\u30e0\u4ed5\u69d8\u306b\u306f\u4e21\u65b9\u304c\u5fc5\u8981\u3067\u3042\u308b\u3002<\/p>\n<h2>\u4e3b\u8981\u306a\u30b3\u30f3\u30bb\u30d7\u30c8\u306e\u8981\u7d04 \ud83d\udcdd<\/h2>\n<table>\n<thead>\n<tr>\n<th>\u30b3\u30f3\u30bb\u30d7\u30c8<\/th>\n<th>\u91cd\u8981\u306a\u30dd\u30a4\u30f3\u30c8<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\u30d7\u30e9\u30a4\u30de\u30ea\u30ad\u30fc<\/td>\n<td>\u884c\u306e\u305f\u3081\u306e\u56fa\u6709ID\u3002null\u306f\u8a31\u53ef\u3055\u308c\u306a\u3044\u3002<\/td>\n<\/tr>\n<tr>\n<td>\u5916\u90e8\u30ad\u30fc<\/td>\n<td>\u5225\u306e\u30c6\u30fc\u30d6\u30eb\u306e\u30d7\u30e9\u30a4\u30de\u30ea\u30ad\u30fc\u3078\u306e\u30ea\u30f3\u30af\u3002<\/td>\n<\/tr>\n<tr>\n<td>\u57fa\u6570<\/td>\n<td>\u6700\u5927\u95a2\u4fc2\u6570\uff081, 1..N\uff09\u3002<\/td>\n<\/tr>\n<tr>\n<td>\u7d50\u5408\u30c6\u30fc\u30d6\u30eb<\/td>\n<td>\u591a\u5bfe\u591a\u95a2\u4fc2\u3092\u89e3\u6c7a\u3057\u307e\u3059\u3002<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u3053\u308c\u3089\u306e\u9055\u3044\u3092\u7fd2\u5f97\u3059\u308b\u3053\u3068\u3067\u3001\u5805\u7262\u306a\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u8a2d\u8a08\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002\u76ee\u7684\u306f\u660e\u78ba\u6027\u3001\u6574\u5408\u6027\u3001\u30b9\u30b1\u30fc\u30e9\u30d3\u30ea\u30c6\u30a3\u3067\u3059\u3002\u30e2\u30c7\u30eb\u304c\u30d3\u30b8\u30cd\u30b9\u306e\u73fe\u5b9f\u3092\u6b63\u78ba\u306b\u53cd\u6620\u3057\u3066\u3044\u308b\u304b\u3092\u78ba\u8a8d\u3059\u308b\u305f\u3081\u306b\u3001\u3053\u308c\u3089\u306e\u70b9\u3092\u3082\u3068\u306b\u56f3\u3092\u78ba\u8a8d\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<p>\u3053\u308c\u3089\u306e15\u306e\u4e00\u822c\u7684\u306a\u8aa4\u89e3\u3092\u89e3\u6d88\u3059\u308b\u3053\u3068\u3067\u3001\u4fdd\u5b88\u30fb\u62e1\u5f35\u304c\u5bb9\u6613\u306a\u30b7\u30b9\u30c6\u30e0\u306e\u57fa\u76e4\u304c\u7bc9\u3051\u307e\u3059\u3002\u30c7\u30fc\u30bf\u306e\u610f\u5473\u8ad6\u306b\u6ce8\u76ee\u3059\u308c\u3070\u3001\u6280\u8853\u7684\u306a\u5b9f\u88c5\u306f\u81ea\u7136\u3068\u5c0e\u304b\u308c\u3066\u304d\u307e\u3059\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u30a8\u30f3\u30c6\u30a3\u30c6\u30a3\u95a2\u4fc2\u56f3\uff08ERD\uff09\u306f\u3001\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3\u306e&hellip;<\/p>\n","protected":false},"author":1,"featured_media":64,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_title":"ER\u56f3\u306e\u8aa4\u89e3\uff1a15\u306e\u30ad\u30fc\u3001\u95a2\u4fc2\u6027\u3001\u57fa\u6570\u306e\u8aac\u660e","_yoast_wpseo_metadesc":"\u4e00\u822c\u7684\u306aERD\u8a2d\u8a08\u306e\u554f\u984c\u3092\u89e3\u6c7a\u3057\u307e\u3059\u3002\u30ad\u30fc\u3001\u57fa\u6570\u3001\u95a2\u4fc2\u6027\u3001\u6b63\u898f\u5316\u306b\u3064\u3044\u3066\u306e\u30ac\u30a4\u30c9\u3067\u3059\u3002\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30a2\u30fc\u30ad\u30c6\u30af\u30c8\u5411\u3051\u306e\u660e\u78ba\u306aQ&A\u3002","inline_featured_image":false,"fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[7],"tags":[8,13],"class_list":["post-63","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-erd","tag-academic","tag-erd"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.1.1 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>ER\u56f3\u306e\u8aa4\u89e3\uff1a15\u306e\u30ad\u30fc\u3001\u95a2\u4fc2\u6027\u3001\u57fa\u6570\u306e\u8aac\u660e<\/title>\n<meta name=\"description\" content=\"\u4e00\u822c\u7684\u306aERD\u8a2d\u8a08\u306e\u554f\u984c\u3092\u89e3\u6c7a\u3057\u307e\u3059\u3002\u30ad\u30fc\u3001\u57fa\u6570\u3001\u95a2\u4fc2\u6027\u3001\u6b63\u898f\u5316\u306b\u3064\u3044\u3066\u306e\u30ac\u30a4\u30c9\u3067\u3059\u3002\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30a2\u30fc\u30ad\u30c6\u30af\u30c8\u5411\u3051\u306e\u660e\u78ba\u306aQ&amp;A\u3002\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.we-notes.com\/ja\/er-diagram-relations-keys-cardinality-guide\/\" \/>\n<meta property=\"og:locale\" content=\"ja_JP\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta 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