{"id":5425,"date":"2025-07-29T01:20:47","date_gmt":"2025-07-28T16:20:47","guid":{"rendered":"https:\/\/sky-peace.net\/?p=5425"},"modified":"2025-07-29T01:20:47","modified_gmt":"2025-07-28T16:20:47","slug":"db-join","status":"publish","type":"post","link":"https:\/\/sky-peace.net\/certified\/db-join\/","title":{"rendered":"\u904e\u53bb\u554f\u306b\u5b66\u3076JOIN\u306e\u51fa\u984c\u30d1\u30bf\u30fc\u30f3\u3068\u89e3\u6cd5\u306e\u30b3\u30c4\uff5cINNER\u30fbLEFT\u30fbRIGHT\u306e\u4f7f\u3044\u5206\u3051\u5b8c\u5168\u30ac\u30a4\u30c9"},"content":{"rendered":"

SQL\u306eJOIN\u6587\u306f\u3001\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u306e\u8907\u6570\u30c6\u30fc\u30d6\u30eb\u3092\u7d50\u3073\u4ed8\u3051\u308b\u5f37\u529b\u306a\u624b\u6bb5\u3067\u3059\u304c\u3001inner join \/ left outer join \/ right outer join<\/strong> \u306e\u9055\u3044\u3092\u6b63\u78ba\u306b\u7406\u89e3\u3057\u3066\u3044\u306a\u3044\u3068\u3001\u8a66\u9a13\u672c\u756a\u3067\u601d\u308f\u306c\u30df\u30b9\u3092\u62db\u304f\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002\u3068\u304f\u306b\u5fdc\u7528\u60c5\u5831\u6280\u8853\u8005\u8a66\u9a13\u3084\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30b9\u30da\u30b7\u30e3\u30ea\u30b9\u30c8\u8a66\u9a13\u3067\u306f\u3001\u51fa\u529b\u7d50\u679c\u3092\u63a8\u6e2c\u3055\u305b\u308b\u30bf\u30a4\u30d7\u306e\u554f\u984c\u304c\u983b\u51fa<\/strong>\u3067\u3059\u3002\u672c\u8a18\u4e8b\u3067\u306f\u3001\u904e\u53bb\u554f\u306b\u767b\u5834\u3057\u305f\u51fa\u984c\u30d1\u30bf\u30fc\u30f3\u3092\u984c\u6750\u306b\u3001\u305d\u308c\u305e\u308c\u306eJOIN\u306e\u4f7f\u3044\u3069\u3053\u308d\u30fb\u3072\u3063\u304b\u3051\u30dd\u30a4\u30f3\u30c8\u30fb\u6b63\u78ba\u306a\u51fa\u529b\u30a4\u30e1\u30fc\u30b8\u3092\u63b4\u3080\u305f\u3081\u306e\u5b9f\u8df5\u7684\u306a\u5b66\u7fd2\u6cd5\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n

1. \u57fa\u790e\u77e5\u8b58\u3068\u308f\u304b\u308a\u3084\u3059\u3044\u89e3\u8aac<\/h2>\n

SQL\u306eJOIN\u53e5\u306b\u306f\u8907\u6570\u306e\u7a2e\u985e\u304c\u3042\u308a\u307e\u3059\u304c\u3001\u8a66\u9a13\u3067\u3088\u304f\u554f\u308f\u308c\u308b\u306e\u306f\u4ee5\u4e0b\u306e3\u3064\u3067\u3059\u3002<\/p>\n

INNER JOIN\uff08\u5185\u90e8\u7d50\u5408\uff09<\/h3>\n

2\u3064\u306e\u30c6\u30fc\u30d6\u30eb\u306b\u304a\u3044\u3066\u3001\u7d50\u5408\u6761\u4ef6\u3092\u6e80\u305f\u3059\u30ec\u30b3\u30fc\u30c9\u306e\u307f<\/strong>\u3092\u53d6\u5f97\u3057\u307e\u3059\u3002\u4e21\u30c6\u30fc\u30d6\u30eb\u306b\u5171\u901a\u3059\u308b\u30c7\u30fc\u30bf\u306b\u9650\u5b9a\u3057\u3066\u7d50\u679c\u3092\u5f97\u305f\u3044\u3068\u304d\u306b\u4f7f\u3044\u307e\u3059\u3002<\/p>\n

SELECT *\nFROM \u5546\u54c1\nINNER JOIN \u6ce8\u6587\n  ON \u5546\u54c1.\u5546\u54c1ID = \u6ce8\u6587.\u5546\u54c1ID;\n<\/code><\/pre>\n
✅ \u4f7f\u7528\u30b7\u30fc\u30f3<\/strong>
\n\u30fb\u300c\u5b9f\u969b\u306b\u6ce8\u6587\u304c\u3042\u3063\u305f\u5546\u54c1\u3060\u3051\u300d\u3092\u62bd\u51fa
\n\u30fb\u4e21\u30c6\u30fc\u30d6\u30eb\u306b\u30c7\u30fc\u30bf\u304c\u3042\u308b\u884c\u3060\u3051\u5fc5\u8981\u306a\u3068\u304d<\/p>\n
LEFT OUTER JOIN\uff08\u5de6\u5916\u90e8\u7d50\u5408\uff09<\/h3>\n
\u5de6\u5074\u306e\u30c6\u30fc\u30d6\u30eb\u306e\u5168\u884c<\/strong>\u3092\u57fa\u6e96\u306b\u3001\u7d50\u5408\u6761\u4ef6\u3092\u6e80\u305f\u3059\u53f3\u5074\u30c6\u30fc\u30d6\u30eb\u306e\u884c\u3092\u5bfe\u5fdc\u4ed8\u3051\u307e\u3059\u3002\u53f3\u5074\u306b\u8a72\u5f53\u304c\u306a\u3044\u5834\u5408\u306fNULL\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n
SELECT *\nFROM \u5546\u54c1\nLEFT OUTER JOIN \u6ce8\u6587\n  ON \u5546\u54c1.\u5546\u54c1ID = \u6ce8\u6587.\u5546\u54c1ID;\n<\/code><\/pre>\n
✅ \u4f7f\u7528\u30b7\u30fc\u30f3<\/strong>
\n\u30fb\u5546\u54c1\u4e00\u89a7\u306b\u300c\u307e\u3060\u58f2\u308c\u3066\u3044\u306a\u3044\u5546\u54c1\u300d\u3082\u8868\u793a\u3057\u305f\u3044
\n\u30fb\u30c7\u30fc\u30bf\u6b20\u640d\u3092\u542b\u3081\u305f\u5168\u4f53\u306e\u53ef\u8996\u5316<\/p>\n
RIGHT OUTER JOIN\uff08\u53f3\u5916\u90e8\u7d50\u5408\uff09<\/h3>\n
LEFT OUTER JOIN\u3068\u5de6\u53f3\u304c\u9006\u3067\u3059\u3002\u53f3\u5074\u306e\u30c6\u30fc\u30d6\u30eb\u306e\u5168\u884c<\/strong>\u304c\u7d50\u679c\u306b\u6b8b\u308a\u3001\u5de6\u5074\u306b\u30de\u30c3\u30c1\u3057\u306a\u3044\u5834\u5408\u306fNULL\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n
SELECT *\nFROM \u5546\u54c1\nRIGHT OUTER JOIN \u6ce8\u6587\n  ON \u5546\u54c1.\u5546\u54c1ID = \u6ce8\u6587.\u5546\u54c1ID;\n<\/code><\/pre>\n
✅ \u4f7f\u7528\u30b7\u30fc\u30f3<\/strong>
\n\u30fb\u300c\u6ce8\u6587\u3055\u308c\u305f\u304c\u3001\u5546\u54c1\u30de\u30b9\u30bf\u306b\u672a\u767b\u9332\u306e\u5546\u54c1\u300d\u304c\u306a\u3044\u304b\u3092\u8abf\u3079\u308b<\/p>\n
🔍 \u7d50\u679c\u30a4\u30e1\u30fc\u30b8\uff08Venn\u56f3\uff09<\/h3>\n
venn\nA[\u5546\u54c1]\nB[\u6ce8\u6587]\nAB[\u5171\u901a]\n<\/code><\/pre>\n
    \n
  • INNER JOIN \u2192 AB<\/li>\n
  • LEFT OUTER JOIN \u2192 A + AB<\/li>\n
  • RIGHT OUTER JOIN \u2192 B + AB<\/li>\n<\/ul>\n
    \u3053\u308c\u3089\u306e\u9055\u3044\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u3067\u3001\u300c\u3069\u306e\u30ec\u30b3\u30fc\u30c9\u304c\u6b8b\u308a\u3001\u3069\u308c\u304cNULL\u306b\u306a\u308b\u304b\u300d<\/strong>\u3092\u6b63\u78ba\u306b\u4e88\u6e2c\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002\u8a66\u9a13\u3067\u306f\u3053\u306e\u4e88\u6e2c\u529b\u304c\u554f\u308f\u308c\u307e\u3059\u3002<\/p>\n
    2. \u904e\u53bb\u306e\u51fa\u984c\u4f8b\uff082\u301c3 \u984c\uff09\u3068\u89e3\u8aac<\/h2>\n
    JOIN\u306b\u95a2\u3059\u308b\u51fa\u984c\u306f\u300c\u51fa\u529b\u7d50\u679c\u306e\u4e88\u6e2c\u300d\u300c\u7d50\u5408\u306e\u6b63\u78ba\u6027\u300d\u300cNULL\u306e\u6271\u3044\u300d\u304c\u554f\u308f\u308c\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001\u904e\u53bb\u554f\u304b\u3089\u4ee3\u8868\u7684\u306a3\u4f8b\u3092\u30d4\u30c3\u30af\u30a2\u30c3\u30d7\u3057\u3001\u51fa\u984c\u610f\u56f3\u3068\u89e3\u6cd5\u306e\u30dd\u30a4\u30f3\u30c8\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n
    \u3010\u4f8b1\u3011\u4ee4\u548c3\u5e74\u79cb \u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30b9\u30da\u30b7\u30e3\u30ea\u30b9\u30c8 \u5348\u524d\u2161 \u554f6<\/h3>\n
    \u8a2d\u554f\u8981\u65e8<\/strong>\uff1a
    \n\u300c\u5546\u54c1\u30c6\u30fc\u30d6\u30eb\u300d\u3068\u300c\u6ce8\u6587\u30c6\u30fc\u30d6\u30eb\u300d\u3092LEFT OUTER JOIN\u3057\u305f\u7d50\u679c\u3001NULL\u304c\u542b\u307e\u308c\u308b\u884c\u304c\u5b58\u5728\u3059\u308b\u3002\u305d\u306e\u7406\u7531\u3092\u9078\u3079\u3002<\/p>\n
    \u30dd\u30a4\u30f3\u30c8<\/strong>\uff1a
    \nLEFT JOIN\u306f\u3001\u5de6\u5074\u306e\u30c6\u30fc\u30d6\u30eb\u306e\u3059\u3079\u3066\u306e\u884c\u3092\u51fa\u529b\u3057\u3001\u53f3\u5074\u306b\u8a72\u5f53\u3059\u308b\u30ec\u30b3\u30fc\u30c9\u304c\u306a\u3051\u308c\u3070NULL\u306b\u306a\u308a\u307e\u3059\u3002\u3064\u307e\u308a\u3001\u6ce8\u6587\u304c\u5b58\u5728\u3057\u306a\u3044\u5546\u54c1\uff08\u672a\u8ca9\u58f2\uff09<\/strong>\u304c\u542b\u307e\u308c\u308b\u3068NULL\u304c\u51fa\u308b\u3002<\/p>\n
    \u6b63\u7b54\u306e\u9078\u3073\u65b9<\/strong>\uff1a
    \n\u30fb\u300c\u5546\u54c1\u306b\u306f\u5b58\u5728\u3059\u308b\u304c\u3001\u6ce8\u6587\u306b\u5b58\u5728\u3057\u306a\u3044\u30c7\u30fc\u30bf\u304c\u3042\u308b\u300d\u2192\u25cb
    \n\u30fb\u300c\u4e21\u65b9\u306b\u5b58\u5728\u3059\u308b\u5834\u5408\u3067\u3082NULL\u306b\u306a\u308b\u300d\u2192\u00d7<\/p>\n
    \u3010\u4f8b2\u3011\u4ee4\u548c\u5143\u5e74\u6625 \u5fdc\u7528\u60c5\u5831\u6280\u8853\u8005 \u5348\u5f8c \u554f4\uff08\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u8a2d\u8a08\uff09<\/h3>\n
    \u8a2d\u554f\u8981\u65e8<\/strong>\uff1a
    \n3\u3064\u306e\u30c6\u30fc\u30d6\u30eb\uff08\u793e\u54e1\u30fb\u90e8\u7f72\u30fb\u5f79\u8077\uff09\u3092JOIN\u3057\u3066\u3001\u7279\u5b9a\u6761\u4ef6\u306b\u4e00\u81f4\u3059\u308b\u793e\u54e1\u4e00\u89a7\u3092\u51fa\u529b\u3002JOIN\u306e\u7a2e\u985e\uff08INNER\/LEFT\uff09\u304c\u6df7\u5728\u3002<\/p>\n
    \u30dd\u30a4\u30f3\u30c8<\/strong>\uff1a
    \n\u8907\u6570JOIN\u6642\u306b\u306fJOIN\u306e\u9806\u5e8f\u3068\u7a2e\u985e\u306b\u3088\u3063\u3066\u7d50\u679c\u304c\u5909\u308f\u308b<\/strong>\u3002INNER JOIN\u540c\u58eb\u3067\u306f\u3001\u3059\u3079\u3066\u306e\u7d50\u5408\u6761\u4ef6\u3092\u6e80\u305f\u3059\u30c7\u30fc\u30bf\u3057\u304b\u6b8b\u3089\u306a\u3044\u3002<\/p>\n
    \u8a66\u9a13\u8005\u306e\u306d\u3089\u3044<\/strong>\uff1a
    \n\u30fb\u300cINNER JOIN \u2192 \u7d5e\u308a\u8fbc\u307e\u308c\u3059\u304e\u308b\u3053\u3068\u304c\u3042\u308b\u300d
    \n\u30fb\u300cLEFT JOIN\u3092\u4f7f\u3048\u3070\u5168\u793e\u54e1\u3092\u51fa\u529b\u53ef\u80fd\u300d<\/p>\n
    \u3010\u4f8b3\u3011\u5e73\u621029\u5e74\u6625 \u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30b9\u30da\u30b7\u30e3\u30ea\u30b9\u30c8 \u5348\u5f8c\u2160 \u554f2<\/h3>\n
    \u8a2d\u554f\u8981\u65e8<\/strong>\uff1a
    \nLEFT JOIN\u306e\u7d50\u679c\u306bGROUP BY\u3068COUNT\u3092\u7d44\u307f\u5408\u308f\u305b\u305fSQL\u3002NULL\u3092\u542b\u3080\u30c7\u30fc\u30bf\u306e\u30ab\u30a6\u30f3\u30c8\u306b\u6ce8\u610f\u304c\u5fc5\u8981\u3002<\/p>\n
    \u843d\u3068\u3057\u7a74<\/strong>\uff1a
    \nNULL\u306fGROUP BY\u306b\u542b\u307e\u308c\u308b\u304c\u3001COUNT(\u5217\u540d)<\/strong> \u306fNULL\u3092\u30ab\u30a6\u30f3\u30c8\u3057\u306a\u3044\u3002
    \n\u2192 \u3064\u307e\u308a\u300cCOUNT(*)\u300d\u3068\u300cCOUNT(\u5217\u540d)\u300d\u306e\u9055\u3044\u3092\u7406\u89e3\u3057\u3066\u3044\u308b\u304b\u304c\u554f\u308f\u308c\u308b\u3002<\/p>\n
    \u3053\u308c\u3089\u306e\u4f8b\u304b\u3089\u3001JOIN\u554f\u984c\u3067\u306e\u91cd\u8981\u306a\u7740\u773c\u70b9\u306f\u6b21\u306e\u901a\u308a\u3067\u3059\uff1a<\/p>\n
      \n
    • NULL\u306b\u306a\u308b\u884c\u306e\u610f\u5473\u3068\u767a\u751f\u30bf\u30a4\u30df\u30f3\u30b0<\/strong><\/li>\n
    • JOIN\u306e\u9806\u5e8f\u30fb\u7a2e\u985e\u306b\u3088\u308b\u51fa\u529b\u7d50\u679c\u306e\u9055\u3044<\/strong><\/li>\n
    • GROUP BY\u3084\u96c6\u8a08\u3068\u306e\u4f75\u7528\u6642\u306e\u5f71\u97ff<\/strong><\/li>\n<\/ul>\n
      \u904e\u53bb\u554f\u3092\u8aad\u3080\u3068\u304d\u306f\u3001\u300cJOIN\u304c\u3069\u3046\u6a5f\u80fd\u3057\u3066\u3044\u308b\u304b\u300d\u2192\u300c\u305d\u306e\u7d50\u679c\u3069\u3046\u51fa\u529b\u3055\u308c\u308b\u304b\u300d<\/strong>\u3092\u610f\u8b58\u3059\u308b\u3053\u3068\u304c\u5f97\u70b9\u3078\u306e\u8fd1\u9053\u3067\u3059\u3002<\/p>\n
      3. \u3064\u307e\u305a\u304d\u30dd\u30a4\u30f3\u30c8\u5fb9\u5e95\u89e3\u8aac<\/h2>\n
      JOIN\u53e5\u306f\u4e00\u898b\u30b7\u30f3\u30d7\u30eb\u306b\u898b\u3048\u307e\u3059\u304c\u3001\u5b9f\u969b\u306e\u8a66\u9a13\u3084\u696d\u52d9\u3067\u306f\u300c\u3042\u308c\uff1f\u306a\u305c\u3053\u306e\u884c\u304c\u51fa\u306a\u3044\uff08\u307e\u305f\u306f\u51fa\u308b\uff09\u3093\u3060\uff1f\u300d<\/strong>\u3068\u3044\u3046\u6df7\u4e71\u304c\u8d77\u304d\u3084\u3059\u3044\u3067\u3059\u3002\u3053\u3053\u3067\u306f\u4ee3\u8868\u7684\u306a\u3064\u307e\u305a\u304d\u30dd\u30a4\u30f3\u30c8\u30923\u3064\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n
      \u2460 LEFT JOIN\u3067NULL\u304c\u8fd4\u308b\u7406\u7531\u304c\u76f4\u611f\u3068\u30ba\u30ec\u308b<\/h3>\n
      LEFT OUTER JOIN\u3092\u4f7f\u3063\u305f\u969b\u3001\u53f3\u5074\u306e\u30c6\u30fc\u30d6\u30eb\u306b\u4e00\u81f4\u3059\u308b\u884c\u304c\u306a\u3051\u308c\u3070\u3001\u8a72\u5f53\u5217\u306bNULL\u304c\u5165\u308a\u307e\u3059<\/strong>\u3002\u3053\u308c\u3092\u898b\u843d\u3068\u3059\u3068\u3001\u300c\u306a\u3093\u3067\u3053\u306e\u884c\u3060\u3051\u5909\u306a\u3093\u3060\uff1f\u300d\u3068\u6df7\u4e71\u3059\u308b\u539f\u56e0\u306b\u3002<\/p>\n
      SELECT \u5546\u54c1.\u5546\u54c1\u540d, \u6ce8\u6587.\u6570\u91cf\nFROM \u5546\u54c1\nLEFT JOIN \u6ce8\u6587\n  ON \u5546\u54c1.\u5546\u54c1ID = \u6ce8\u6587.\u5546\u54c1ID;\n<\/code><\/pre>\n
      \u2192 \u6ce8\u6587\u304c\u306a\u3044\u5546\u54c1\u306f\u3001\u6570\u91cf\u304cNULL\u3067\u51fa\u529b\u3055\u308c\u308b<\/strong><\/p>\n
      ✅ NULL\u306f\u300c\u5b58\u5728\u3057\u306a\u3044\u300d\u3053\u3068\u306e\u660e\u793a\u3002\u9593\u9055\u3044\u3067\u306f\u306a\u3044\u3002<\/strong><\/p>\n
      \u2461 ON\u53e5\u3068WHERE\u53e5\u306e\u4f75\u7528\u3067INNER JOIN\u5316\u3057\u3066\u3057\u307e\u3046<\/h3>\n
      LEFT JOIN\u3068\u4f75\u7528\u3059\u308bWHERE\u53e5\u306b\u6ce8\u610f\u3057\u306a\u3044\u3068\u3001\u305b\u3063\u304b\u304f\u306e\u5916\u90e8\u7d50\u5408\u304c\u7121\u52b9\u306b\u306a\u308b<\/strong>\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n
      -- NG\u4f8b\uff1aLEFT JOIN\u306e\u610f\u5473\u304c\u306a\u304f\u306a\u308b\nSELECT *\nFROM \u5546\u54c1\nLEFT JOIN \u6ce8\u6587\n  ON \u5546\u54c1.\u5546\u54c1ID = \u6ce8\u6587.\u5546\u54c1ID\nWHERE \u6ce8\u6587.\u6570\u91cf > 10;\n<\/code><\/pre>\n
      \u2192 \u3053\u306e\u5834\u5408\u3001\u6ce8\u6587.\u6570\u91cf<\/code>\u304cNULL\u306e\u884c\uff08\u672a\u6ce8\u6587\u306e\u5546\u54c1\uff09\u304c\u6d88\u3048\u3066\u3057\u307e\u3044\u3001\u5b9f\u8ceaINNER JOIN\u3068\u540c\u3058\u632f\u308b\u821e\u3044\u306b\u3002<\/p>\n
      ✅ WHERE\u6761\u4ef6\u306bNULL\u3092\u6392\u9664\u3059\u308b\u30ed\u30b8\u30c3\u30af\u304c\u3042\u308b\u3068\u6ce8\u610f\uff01<\/strong><\/p>\n
      \u2462 GROUP BY\u3084COUNT\u3068\u306e\u4f75\u7528\u3067\u96c6\u8a08\u304c\u305a\u308c\u308b<\/h3>\n
      JOIN\u7d50\u679c\u306b\u96c6\u8a08\u95a2\u6570\u3092\u4f7f\u3046\u5834\u5408\u3001COUNT\u306e\u5bfe\u8c61\u5217\u304cNULL\u304b\u3069\u3046\u304b\u3067\u96c6\u8a08\u7d50\u679c\u304c\u5909\u308f\u308a\u307e\u3059\u3002<\/strong><\/p>\n
      -- NULL\u3092\u542b\u3081\u305f\u4ef6\u6570\u304c\u77e5\u308a\u305f\u3044\u306a\u3089 COUNT(*) \u3092\u4f7f\u3046\nSELECT \u5546\u54c1.\u5546\u54c1\u540d, COUNT(\u6ce8\u6587.\u6570\u91cf)\nFROM \u5546\u54c1\nLEFT JOIN \u6ce8\u6587\n  ON \u5546\u54c1.\u5546\u54c1ID = \u6ce8\u6587.\u5546\u54c1ID\nGROUP BY \u5546\u54c1.\u5546\u54c1\u540d;\n<\/code><\/pre>\n
      \u2192 COUNT(\u6ce8\u6587.\u6570\u91cf)<\/code> \u306f NULL \u3092\u30ab\u30a6\u30f3\u30c8\u3057\u306a\u3044\u3002COUNT(*)<\/code>\u306a\u3089\u884c\u6570\u30ab\u30a6\u30f3\u30c8\u3068\u306a\u308b\u3002<\/p>\n
      ✅ \u4f55\u3092\u6570\u3048\u305f\u3044\u306e\u304b\uff1fNULL\u3092\u542b\u3081\u305f\u3044\u306e\u304b\uff1f\u3092\u660e\u78ba\u306b<\/strong><\/p>\n
      4. \u4eca\u5f8c\u306e\u51fa\u984c\u4e88\u60f3\u3068\u4f8b\u984c<\/h2>\n
      SQL\u306e\u51fa\u984c\u306f\u5e74\u3005\u300c\u69cb\u6587\u306e\u6697\u8a18\u300d\u304b\u3089\u300c\u696d\u52d9\u8981\u4ef6\u306b\u6cbf\u3063\u305f\u5b9f\u88c5\u306e\u6b63\u3057\u3055\u300d\u3092\u554f\u3046\u50be\u5411\u306b\u30b7\u30d5\u30c8\u3057\u3066\u3044\u307e\u3059\u3002JOIN\u306b\u95a2\u3057\u3066\u3082\u3001\u5358\u306a\u308b\u6587\u6cd5\u7406\u89e3\u3067\u306f\u306a\u304f\u201c\u72b6\u6cc1\u306b\u5fdc\u3058\u305f\u4f7f\u3044\u5206\u3051\u201d<\/strong>\u304c\u554f\u308f\u308c\u308b\u3068\u8003\u3048\u3089\u308c\u307e\u3059\u3002<\/p>\n
      🔮 \u51fa\u984c\u30c8\u30ec\u30f3\u30c9\u4e88\u6e2c<\/h3>\n
      ✅ RIGHT OUTER JOIN\u306e\u767b\u5834\u7387UP<\/h4>\n
      \u904e\u53bb\u554f\u3067\u306fLEFT JOIN\u306e\u51fa\u984c\u304c\u591a\u3044\u3067\u3059\u304c\u3001RIGHT JOIN\u304c\u300c\u4f7f\u3044\u6163\u308c\u3066\u3044\u306a\u3044\uff1d\u3072\u3063\u304b\u3051\u3084\u3059\u3044\u300d\u3068\u3057\u3066\u4eca\u5f8c\u306e\u51fa\u984c\u304c\u4e88\u60f3\u3055\u308c\u307e\u3059\u3002<\/p>\n