{"id":1413,"date":"2026-07-19T12:00:00","date_gmt":"2026-07-19T03:00:00","guid":{"rendered":"https:\/\/www.ecoop.net\/memo\/?p=1413"},"modified":"2026-07-20T00:00:16","modified_gmt":"2026-07-19T15:00:16","slug":"inner-join-left-join","status":"publish","type":"post","link":"https:\/\/www.ecoop.net\/memo\/archives\/inner-join-left-join.html","title":{"rendered":"INNER JOIN \u3068 LEFT JOIN \u306e\u9055\u3044 \u2014 \u7d50\u679c\u304c\u3069\u3046\u5909\u308f\u308b\u304b\u5b9f\u4f8b\u3067\u78ba\u8a8d"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">INNER JOIN \u3068 LEFT JOIN \u306e\u9055\u3044\u306f\u4e00\u8a00\u3067\u3044\u3046\u3068\u3001\u76f8\u624b\u306e\u3044\u306a\u3044\u884c\u3092\u7d50\u679c\u306b\u6b8b\u3059\u304b\u3069\u3046\u304b\u3067\u3059\u3002INNER JOIN(\u5185\u90e8\u7d50\u5408)\u306f\u4e21\u65b9\u306e\u30c6\u30fc\u30d6\u30eb\u306b\u5bfe\u5fdc\u3059\u308b\u884c\u304c\u3042\u308b\u3082\u306e\u3060\u3051\u3092\u8fd4\u3057\u3001LEFT JOIN(\u5de6\u5916\u90e8\u7d50\u5408)\u306f\u5de6\u306e\u30c6\u30fc\u30d6\u30eb\u306e\u884c\u3092\u5168\u90e8\u6b8b\u3057\u3066\u3001\u76f8\u624b\u304c\u3044\u306a\u3044\u884c\u306f\u53f3\u5074\u306e\u5217\u3092 NULL \u3067\u57cb\u3081\u307e\u3059(\u3053\u308c\u3092 NULL \u30d1\u30c7\u30a3\u30f3\u30b0\u3068\u547c\u3073\u307e\u3059)\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u306e\u8a18\u4e8b\u3067\u306f\u540c\u3058\u30c7\u30fc\u30bf\u306b\u4e21\u65b9\u3092\u5b9f\u884c\u3057\u3066\u7d50\u679c\u3092\u898b\u6bd4\u3079\u305f\u3042\u3068\u3001\u6761\u4ef6\u3092 ON \u306b\u66f8\u304f\u304b WHERE \u306b\u66f8\u304f\u304b\u3067 LEFT JOIN \u306e\u7d50\u679c\u304c\u5909\u308f\u308b\u7f60\u3068\u3001\u300cLEFT JOIN \u306f\u9045\u3044\u306e\u304b\u300d\u3068\u3044\u3046\u7591\u554f\u3092\u6271\u3044\u307e\u3059\u3002\u5b9f\u884c\u7d50\u679c\u306f\u3059\u3079\u3066 PostgreSQL 17.10 \u3067\u5b9f\u969b\u306b\u78ba\u8a8d\u3057\u305f\u3082\u306e\u3067\u3001ON \u3068 WHERE \u306e\u7f60\u306b\u3064\u3044\u3066\u306f MySQL 8.4.10 \u3067\u3082\u540c\u3058\u7d50\u679c\u306b\u306a\u308b\u3053\u3068\u3092\u78ba\u8a8d\u3057\u3066\u3044\u307e\u3059\u3002JOIN \u5168\u7a2e\u985e\u306e\u307e\u3068\u3081\u306f <a href=\"\/memo\/archives\/2007-11-14-1.html\">SQL \u306e JOIN \u306e\u7a2e\u985e\u3068\u9055\u3044\u307e\u3068\u3081 \u2014 INNER\/LEFT\/RIGHT\/FULL\/CROSS\u30102026\u5e74\u66f4\u65b0\u3011<\/a> \u306b\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u30b5\u30f3\u30d7\u30eb\u30c7\u30fc\u30bf<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u793e\u54e1\u8868 emp \u3068\u90e8\u7f72\u8868 dept \u3092\u4f7f\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<!--more-->\n\n\n\n<pre class=\"wp-block-preformatted\">CREATE TABLE emp (id INT, name VARCHAR(20), dept_id INT);\nCREATE TABLE dept (dept_id INT, dept_name VARCHAR(20));\nINSERT INTO emp VALUES (1,'\u4f50\u85e4',10),(2,'\u9234\u6728',20),(3,'\u9ad8\u6a4b',NULL),(4,'\u7530\u4e2d',40);\nINSERT INTO dept VALUES (10,'\u55b6\u696d\u90e8'),(20,'\u958b\u767a\u90e8'),(30,'\u7dcf\u52d9\u90e8');\n<\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u308f\u3056\u3068\u5bfe\u5fdc\u306e\u5d29\u308c\u305f\u884c\u3092\u5165\u308c\u3066\u3042\u308a\u307e\u3059\u3002\u9ad8\u6a4b\u306f dept_id \u304c NULL(\u90e8\u7f72\u672a\u5b9a)\u3001\u7530\u4e2d\u306e dept_id 40 \u306f dept \u5074\u306b\u5b58\u5728\u3057\u307e\u305b\u3093\u3002\u3053\u306e2\u4eba\u306e\u6271\u3044\u306b INNER \u3068 LEFT \u306e\u5dee\u304c\u51fa\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u540c\u3058\u30c7\u30fc\u30bf\u3067\u306e\u7d50\u679c\u6bd4\u8f03<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u307e\u305a INNER JOIN \u3067\u3059\u3002<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">SELECT * FROM emp INNER JOIN dept USING(dept_id);\n<\/pre>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>dept_id<\/th><th>id<\/th><th>name<\/th><th>dept_name<\/th><\/tr><\/thead><tbody><tr><td>10<\/td><td>1<\/td><td>\u4f50\u85e4<\/td><td>\u55b6\u696d\u90e8<\/td><\/tr><tr><td>20<\/td><td>2<\/td><td>\u9234\u6728<\/td><td>\u958b\u767a\u90e8<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">2\u884c\u3060\u3051\u306b\u306a\u308a\u307e\u3057\u305f\u3002dept_id \u304c\u4e21\u65b9\u306e\u30c6\u30fc\u30d6\u30eb\u3067\u4e00\u81f4\u3057\u305f\u884c\u3001\u3064\u307e\u308a\u4f50\u85e4\u3068\u9234\u6728\u3060\u3051\u3067\u3059\u3002\u9ad8\u6a4b(dept_id \u304c NULL)\u3068\u7530\u4e2d(dept_id 40 \u306f dept \u306b\u7121\u3044)\u306f\u7d50\u5408\u76f8\u624b\u304c\u3044\u306a\u3044\u306e\u3067\u3001\u7d50\u679c\u304b\u3089\u6d88\u3048\u307e\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u6b21\u306b\u3001\u540c\u3058\u30af\u30a8\u30ea\u306e INNER \u3092 LEFT \u306b\u5909\u3048\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">SELECT * FROM emp LEFT JOIN dept USING(dept_id);\n<\/pre>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>dept_id<\/th><th>id<\/th><th>name<\/th><th>dept_name<\/th><\/tr><\/thead><tbody><tr><td>10<\/td><td>1<\/td><td>\u4f50\u85e4<\/td><td>\u55b6\u696d\u90e8<\/td><\/tr><tr><td>20<\/td><td>2<\/td><td>\u9234\u6728<\/td><td>\u958b\u767a\u90e8<\/td><\/tr><tr><td>NULL<\/td><td>3<\/td><td>\u9ad8\u6a4b<\/td><td>NULL<\/td><\/tr><tr><td>40<\/td><td>4<\/td><td>\u7530\u4e2d<\/td><td>NULL<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\u4eca\u5ea6\u306f4\u884c\u3067\u3059\u3002\u5de6\u306e\u30c6\u30fc\u30d6\u30eb emp \u306e\u884c\u306f\u76f8\u624b\u304c\u3044\u306a\u304f\u3066\u3082\u5168\u90e8\u6b8b\u308a\u3001\u9ad8\u6a4b\u3068\u7530\u4e2d\u306f dept \u5074\u306e\u5217(dept_name)\u304c NULL \u3067\u57cb\u3081\u3089\u308c\u3066\u3044\u307e\u3059\u3002\u3053\u308c\u304c LEFT JOIN \u3067\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u306a\u304a <code>USING(dept_id)<\/code> \u3067\u7d50\u5408\u3057\u3066\u3044\u308b\u305f\u3081\u3001\u7d50\u5408\u30ad\u30fc\u306e dept_id \u306f\u7d50\u679c\u306e\u5148\u982d\u306b1\u56de\u3060\u3051\u73fe\u308c\u307e\u3059\u3002<code>ON e.dept_id = d.dept_id<\/code> \u3068\u66f8\u3044\u305f\u5834\u5408\u306f\u4e21\u30c6\u30fc\u30d6\u30eb\u306e dept_id \u304c2\u56de\u73fe\u308c\u307e\u3059\u3002INNER JOIN \u306a\u30892\u5217\u3068\u3082\u540c\u3058\u5024\u3067\u3059\u304c\u3001LEFT JOIN \u306e\u76f8\u624b\u306a\u3057\u884c\u3067\u306f\u53f3\u30c6\u30fc\u30d6\u30eb\u5074\u306e dept_id \u306f NULL \u306b\u306a\u308b(\u7530\u4e2d\u306a\u3089 emp \u5074\u306f 40\u3001dept \u5074\u306f NULL)\u306e\u3067\u3001\u3069\u3061\u3089\u306e dept_id \u3092 SELECT \u3059\u308b\u304b\u306b\u6ce8\u610f\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u3061\u306a\u307f\u306b LEFT JOIN \u306f LEFT OUTER JOIN \u306e\u7701\u7565\u5f62\u3067\u3001OUTER \u3092\u66f8\u3044\u3066\u3082\u66f8\u304b\u306a\u304f\u3066\u3082\u610f\u5473\u306f\u5909\u308f\u308a\u307e\u305b\u3093\u3002\u30ad\u30fc\u30ef\u30fc\u30c9\u306e\u7701\u7565\u30eb\u30fc\u30eb\u306f <a href=\"\/memo\/archives\/sql-join-shorthand.html\">SQL \u306e JOIN \u306f\u7701\u7565\u3067\u304d\u308b \u2014 INNER\/OUTER \u30ad\u30fc\u30ef\u30fc\u30c9\u3068\u30ab\u30f3\u30de\u7d50\u5408\u306e\u6574\u7406<\/a> \u306b\u307e\u3068\u3081\u307e\u3057\u305f\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">RIGHT JOIN \u306f LEFT JOIN \u306e\u5de6\u53f3\u53cd\u8ee2\u3067\u3001\u53f3\u306e\u30c6\u30fc\u30d6\u30eb\u306e\u884c\u3092\u5168\u90e8\u6b8b\u3057\u307e\u3059\u3002<code>FROM emp RIGHT JOIN dept<\/code> \u306f <code>FROM dept LEFT JOIN emp<\/code> \u3068\u30c6\u30fc\u30d6\u30eb\u9806\u3092\u5165\u308c\u66ff\u3048\u308c\u3070\u540c\u3058\u884c\u306e\u7d44\u3092 LEFT \u3067\u66f8\u3051\u308b\u306e\u3067(<code>SELECT *<\/code> \u3067\u306f\u5217\u306e\u4e26\u3073\u9806\u3060\u3051\u5909\u308f\u308a\u307e\u3059)\u3001\u5b9f\u52d9\u3067\u306f LEFT \u306b\u7d71\u4e00\u3057\u3066\u66f8\u304f\u3053\u3068\u304c\u591a\u3044\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u7f60:\u6761\u4ef6\u3092 ON \u306b\u66f8\u304f\u304b WHERE \u306b\u66f8\u304f\u304b\u3067\u7d50\u679c\u304c\u5909\u308f\u308b<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u3053\u3053\u304c\u672c\u984c\u3067\u3059\u3002INNER JOIN \u3067\u306f\u7d50\u5408\u6761\u4ef6\u4ee5\u5916\u306e\u6761\u4ef6\u3092 ON \u306b\u8db3\u3057\u3066\u3082 WHERE \u306b\u66f8\u3044\u3066\u3082\u7d50\u679c\u306f\u540c\u3058\u3067\u3059\u304c\u3001<strong>LEFT JOIN \u3067\u306f ON \u3068 WHERE \u3067\u7d50\u679c\u304c\u5909\u308f\u308a\u307e\u3059<\/strong>\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u300c\u55b6\u696d\u90e8\u300d\u306b\u95a2\u3059\u308b\u6761\u4ef6\u3092\u3001\u307e\u305a ON \u306b\u66f8\u3044\u3066\u307f\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">SELECT e.name, d.dept_name FROM emp e\n  LEFT JOIN dept d ON e.dept_id = d.dept_id AND d.dept_name = '\u55b6\u696d\u90e8';\n<\/pre>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>name<\/th><th>dept_name<\/th><\/tr><\/thead><tbody><tr><td>\u4f50\u85e4<\/td><td>\u55b6\u696d\u90e8<\/td><\/tr><tr><td>\u9234\u6728<\/td><td>NULL<\/td><\/tr><tr><td>\u9ad8\u6a4b<\/td><td>NULL<\/td><\/tr><tr><td>\u7530\u4e2d<\/td><td>NULL<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">4\u884c\u3067\u3059\u3002ON \u306e\u6761\u4ef6\u306f\u300c\u3069\u306e\u884c\u3092\u7d50\u5408\u76f8\u624b\u3068\u3057\u3066\u63a1\u7528\u3059\u308b\u304b\u300d\u306e\u9078\u5225\u306b\u4f7f\u308f\u308c\u308b\u3060\u3051\u306a\u306e\u3067\u3001\u5de6\u30c6\u30fc\u30d6\u30eb\u306e\u884c\u306f\u843d\u3061\u307e\u305b\u3093\u3002\u6761\u4ef6\u306b\u5408\u308f\u306a\u304b\u3063\u305f\u9234\u6728\u306f\u3001\u76f8\u624b\u306a\u3057\u6271\u3044\u306b\u306a\u3063\u3066 NULL \u304c\u4ed8\u304f\u3060\u3051\u3067\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u540c\u3058\u6761\u4ef6\u3092 WHERE \u306b\u79fb\u3059\u3068\u3053\u3046\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">SELECT e.name, d.dept_name FROM emp e\n  LEFT JOIN dept d ON e.dept_id = d.dept_id WHERE d.dept_name = '\u55b6\u696d\u90e8';\n<\/pre>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>name<\/th><th>dept_name<\/th><\/tr><\/thead><tbody><tr><td>\u4f50\u85e4<\/td><td>\u55b6\u696d\u90e8<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">1\u884c\u3060\u3051\u306b\u306a\u308a\u307e\u3057\u305f\u3002WHERE \u306f\u7d50\u5408\u304c\u7d42\u308f\u3063\u305f\u3042\u3068\u306e\u7d50\u679c\u306b\u5bfe\u3059\u308b\u30d5\u30a3\u30eb\u30bf\u3067\u3059\u3002dept_name \u304c NULL \u306e\u884c\u306f <code>= '\u55b6\u696d\u90e8'<\/code> \u306e\u6bd4\u8f03\u3092\u6e80\u305f\u305b\u306a\u3044\u306e\u3067\u5168\u90e8\u843d\u3061\u3001\u7d50\u679c\u3068\u3057\u3066 INNER JOIN \u3068\u540c\u3058\u306b\u306a\u308a\u307e\u3059\u3002\u305b\u3063\u304b\u304f LEFT JOIN \u306b\u3057\u305f\u610f\u5473\u304c\u6d88\u3048\u308b\u308f\u3051\u3067\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">PostgreSQL \u306e\u516c\u5f0f\u30de\u30cb\u30e5\u30a2\u30eb\u306b\u3082\u3001ON \u306e\u6761\u4ef6\u306f\u7d50\u5408\u524d\u306b\u3001WHERE \u306e\u6761\u4ef6\u306f\u7d50\u5408\u5f8c\u306b\u51e6\u7406\u3055\u308c\u308b\u3001\u5185\u90e8\u7d50\u5408\u3067\u306f\u9055\u3044\u304c\u306a\u3044\u304c\u5916\u90e8\u7d50\u5408\u3067\u306f\u5927\u304d\u304f\u9055\u3046\u3001\u3068\u660e\u8a18\u3055\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4f7f\u3044\u5206\u3051\u306f\u3053\u3046\u899a\u3048\u3066\u304f\u3060\u3055\u3044\u3002\u5de6\u30c6\u30fc\u30d6\u30eb\u306e\u884c\u3092\u6b8b\u3057\u305f\u307e\u307e\u53f3\u30c6\u30fc\u30d6\u30eb\u5074\u3092\u7d5e\u308a\u305f\u3044\u306a\u3089 ON \u306b\u66f8\u304f\u3002\u7d50\u5408\u5f8c\u306e\u7d50\u679c\u3092\u7d5e\u308a\u305f\u3044\u306a\u3089 WHERE \u306b\u66f8\u304f(\u305d\u3057\u3066\u305d\u306e\u5834\u5408\u3001\u5b9f\u306f INNER JOIN \u3067\u8db3\u308a\u3066\u3044\u308b\u3053\u3068\u304c\u591a\u3044)\u3002\u300cLEFT JOIN \u3057\u305f\u306e\u306b\u884c\u304c\u6e1b\u3063\u305f\u300d\u3068\u3044\u3046\u3068\u304d\u306f\u3001\u307e\u305a WHERE \u306b\u53f3\u30c6\u30fc\u30d6\u30eb\u306e\u6761\u4ef6\u304c\u7d1b\u308c\u3066\u3044\u306a\u3044\u304b\u3092\u7591\u3063\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">LEFT JOIN \u306f INNER JOIN \u3088\u308a\u9045\u3044?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u300cLEFT JOIN \u306f\u9045\u3044\u304b\u3089 INNER JOIN \u306b\u66f8\u304d\u63db\u3048\u308b\u3079\u304d\u300d\u3068\u3044\u3046\u8a71\u3092\u898b\u304b\u3051\u307e\u3059\u304c\u3001\u305d\u306e\u307e\u307e\u3067\u306f\u6b63\u3057\u304f\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5148\u307b\u3069\u306e\u300cWHERE \u306b\u53f3\u30c6\u30fc\u30d6\u30eb\u306e\u6761\u4ef6\u3092\u66f8\u3044\u305f LEFT JOIN\u300d\u3092 PostgreSQL 17 \u3067 EXPLAIN \u3059\u308b\u3068\u3001\u5b9f\u884c\u8a08\u753b\u306f Hash Join \u306b\u306a\u308a\u307e\u3059\u3002Hash Left Join \u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002WHERE \u306e\u6761\u4ef6\u3067 NULL \u30d1\u30c7\u30a3\u30f3\u30b0\u3055\u308c\u305f\u884c\u304c\u3069\u3046\u305b\u6b8b\u308c\u306a\u3044\u3068\u30aa\u30d7\u30c6\u30a3\u30de\u30a4\u30b6\u304c\u5224\u65ad\u3059\u308b\u3068\u3001LEFT JOIN \u306f\u5185\u90e8\u7684\u306b INNER JOIN \u3078\u5909\u63db\u3055\u308c\u308b\u304b\u3089\u3067\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u3064\u307e\u308a\u3001\u540c\u3058\u7d50\u679c\u3092\u8fd4\u3059\u30af\u30a8\u30ea\u3067\u3042\u308c\u3070 INNER \u3068 LEFT \u306b\u539f\u7406\u7684\u306a\u901f\u5ea6\u5dee\u306f\u307b\u307c\u3042\u308a\u307e\u305b\u3093\u3002\u9006\u306b\u7d50\u679c\u304c\u9055\u3046\u30af\u30a8\u30ea\u540c\u58eb(2\u884c\u8fd4\u308b\u3082\u306e\u30684\u884c\u8fd4\u308b\u3082\u306e)\u306e\u901f\u5ea6\u3092\u6bd4\u3079\u3066\u3082\u610f\u5473\u304c\u3042\u308a\u307e\u305b\u3093\u3002\u66f8\u304d\u5206\u3051\u306e\u57fa\u6e96\u306f\u901f\u5ea6\u3067\u306f\u306a\u304f\u3001\u524d\u306e\u7bc0\u307e\u3067\u3067\u898b\u3066\u304d\u305f\u300c\u3069\u306e\u884c\u3092\u6b8b\u3057\u305f\u3044\u304b\u300d\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u4f7f\u3044\u5206\u3051\u306e\u6307\u91dd<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u7d50\u5408\u76f8\u624b\u304c\u5fc5\u305a\u5b58\u5728\u3059\u308b\u30c7\u30fc\u30bf(\u5916\u90e8\u30ad\u30fc\u5236\u7d04\u306a\u3069\u3067\u5bfe\u5fdc\u304c\u4fdd\u8a3c\u3055\u308c\u3066\u3044\u308b\u89aa\u5b50)\u3092\u7a81\u304d\u5408\u308f\u305b\u308b\u306a\u3089 INNER JOIN\u3002\u5bfe\u5fdc\u306e\u7121\u3044\u884c\u304c\u6df7\u3056\u308a\u3088\u3046\u304c\u306a\u3044\u306e\u3067\u3001\u610f\u56f3\u304c\u305d\u306e\u307e\u307e\u4f1d\u308f\u308a\u307e\u3059\u3002<\/li>\n\n\n\n<li>\u76f8\u624b\u304c\u3044\u306a\u3044\u884c\u3082\u898b\u305f\u3044\u306a\u3089 LEFT JOIN\u3002\u300c\u90e8\u7f72\u672a\u5b9a\u306e\u793e\u54e1\u3082\u4e00\u89a7\u306b\u51fa\u3059\u300d\u300c\u6ce8\u6587\u304c1\u4ef6\u3082\u7121\u3044\u9867\u5ba2\u3082\u96c6\u8a08\u306b\u542b\u3081\u308b\u300d\u3068\u3044\u3063\u305f\u5834\u9762\u3067\u3059\u3002\u76f8\u624b\u304c\u3044\u306a\u3044\u884c\u3060\u3051\u3092\u63a2\u3059(dept_name IS NULL \u3067\u7d5e\u308b)\u3068\u3044\u3046\u6b20\u640d\u30c1\u30a7\u30c3\u30af\u306b\u3082\u4f7f\u3048\u307e\u3059\u3002<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u8ff7\u3063\u305f\u3089\u300c\u76f8\u624b\u306e\u3044\u306a\u3044\u884c\u3092\u7d50\u679c\u306b\u51fa\u3057\u305f\u3044\u304b\u300d\u3092\u81ea\u554f\u3059\u308c\u3070\u6c7a\u307e\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u3055\u3044\u3054\u306b<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">INNER JOIN \u306f\u4e21\u65b9\u306b\u5bfe\u5fdc\u3059\u308b\u884c\u3060\u3051\u3001LEFT JOIN \u306f\u5de6\u306e\u5168\u884c+\u76f8\u624b\u306a\u3057\u306f NULL\u3001\u3068\u3044\u3046\u306e\u304c\u57fa\u672c\u306e\u9055\u3044\u3067\u3059\u3002\u305d\u308c\u306b\u52a0\u3048\u3066\u3001LEFT JOIN \u3067\u306f\u6761\u4ef6\u3092 ON \u306b\u7f6e\u304f\u304b WHERE \u306b\u7f6e\u304f\u304b\u3067\u7d50\u679c\u304c\u5909\u308f\u308b\u3053\u3068\u3001\u901f\u5ea6\u306f\u66f8\u304d\u5206\u3051\u306e\u57fa\u6e96\u306b\u306a\u3089\u306a\u3044\u3053\u3068\u3001\u3053\u306e2\u70b9\u3092\u62bc\u3055\u3048\u3066\u304a\u3051\u3070\u5b9f\u52d9\u3067\u56f0\u308b\u3053\u3068\u306f\u307b\u307c\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u3042\u308f\u305b\u3066\u8aad\u307f\u305f\u3044:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"\/memo\/archives\/2007-11-14-1.html\">SQL \u306e JOIN \u306e\u7a2e\u985e\u3068\u9055\u3044\u307e\u3068\u3081 \u2014 INNER\/LEFT\/RIGHT\/FULL\/CROSS\u30102026\u5e74\u66f4\u65b0\u3011<\/a><\/li>\n\n\n\n<li><a href=\"\/memo\/archives\/sql-join-shorthand.html\">SQL \u306e JOIN \u306f\u7701\u7565\u3067\u304d\u308b \u2014 INNER\/OUTER \u30ad\u30fc\u30ef\u30fc\u30c9\u3068\u30ab\u30f3\u30de\u7d50\u5408\u306e\u6574\u7406<\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>INNER JOIN \u3068 LEFT JOIN \u306e\u9055\u3044\u306f\u4e00\u8a00\u3067\u3044\u3046\u3068\u3001\u76f8\u624b\u306e\u3044\u306a\u3044\u884c\u3092\u7d50\u679c\u306b\u6b8b\u3059\u304b\u3069\u3046\u304b\u3067\u3059\u3002INNER JOIN(\u5185\u90e8\u7d50\u5408)\u306f\u4e21\u65b9\u306e\u30c6\u30fc\u30d6\u30eb\u306b\u5bfe\u5fdc\u3059\u308b\u884c\u304c\u3042\u308b\u3082\u306e\u3060\u3051\u3092\u8fd4\u3057\u3001LEFT JOIN(\u5de6\u5916\u90e8\u7d50\u5408 &hellip; <a href=\"https:\/\/www.ecoop.net\/memo\/archives\/inner-join-left-join.html\" class=\"more-link\">\u7d9a\u304d\u3092\u8aad\u3080 <span class=\"screen-reader-text\">INNER JOIN \u3068 LEFT JOIN \u306e\u9055\u3044 \u2014 \u7d50\u679c\u304c\u3069\u3046\u5909\u308f\u308b\u304b\u5b9f\u4f8b\u3067\u78ba\u8a8d<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[89,135],"tags":[],"class_list":["post-1413","post","type-post","status-publish","format-standard","hentry","category-web-dev","category-server"],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.ecoop.net\/memo\/wp-json\/wp\/v2\/posts\/1413","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ecoop.net\/memo\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ecoop.net\/memo\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ecoop.net\/memo\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ecoop.net\/memo\/wp-json\/wp\/v2\/comments?post=1413"}],"version-history":[{"count":2,"href":"https:\/\/www.ecoop.net\/memo\/wp-json\/wp\/v2\/posts\/1413\/revisions"}],"predecessor-version":[{"id":1426,"href":"https:\/\/www.ecoop.net\/memo\/wp-json\/wp\/v2\/posts\/1413\/revisions\/1426"}],"wp:attachment":[{"href":"https:\/\/www.ecoop.net\/memo\/wp-json\/wp\/v2\/media?parent=1413"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ecoop.net\/memo\/wp-json\/wp\/v2\/categories?post=1413"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ecoop.net\/memo\/wp-json\/wp\/v2\/tags?post=1413"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}