{"provider_url":"https://hatena.blog","author_name":"a4dosanddos","blog_title":"\u30d7\u30ed\u30b0\u30e9\u30e0\u65e5\u8a18","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fa4dosanddos.hatenablog.com%2Fentry%2F2022%2F04%2F01%2F233522\" title=\"\u300cSQL\u300dJOIN\u3068EXISTS\u306e\u5099\u5fd8\u9332\u3002 - \u30d7\u30ed\u30b0\u30e9\u30e0\u65e5\u8a18\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","published":"2022-04-01 23:35:22","width":"100%","categories":["Database"],"version":"1.0","image_url":null,"blog_url":"https://a4dosanddos.hatenablog.com/","type":"rich","description":"SQL \u306e JOIN \u3068 EXISTS \u306e\u5099\u5fd8\u9332\u3002 JOIN \u30c6\u30fc\u30d6\u30eb\u7d50\u5408\u306b\u5229\u7528\u3059\u308b\u3002INNER JOIN \u3068 LEFT(RIGHT) OUTER JOIN \u306e\uff12\u7a2e\u985e\u304c\u3042\u308b\u3002 \u4ee5\u4e0b\u306eusers\u3001role\u3001department \u30c6\u30fc\u30d6\u30eb\u3092\u60f3\u5b9a\u3057\u307e\u3059\u3002 test_db=# select * from users ; id | name | role_id | department_id ----+---------+---------+--------------- 1 | name_a | 1 | 100 2 | name_b | 2 | 200 3 | name_c | 3 | 100 4 |\u2026","author_url":"https://blog.hatena.ne.jp/a4dosanddos/","url":"https://a4dosanddos.hatenablog.com/entry/2022/04/01/233522","title":"\u300cSQL\u300dJOIN\u3068EXISTS\u306e\u5099\u5fd8\u9332\u3002","provider_name":"Hatena Blog","height":"190"}