[SQL] JOINについて

JOINの種類

• 内部結合（Inner Join）
• 外部結合（Outer Join）
  • Left Join
  • Right Join
• クロス結合（Cross Join）

Inner Joinの書き方

SELECT * FROM table1 AS a, table2 AS b WHERE a.id = b.id;

または

SELECT * FROM table1 AS a JOIN table2 AS b ON a.id = b.id;

Outer Joinの書き方

SELECT * FROM table1 AS a LEFT JOIN table2 as b ON a.id = b.id;

Cross Joinの書き方

SELECT * FROM table1, table2;

または

SELECT * FROM table1 CROSS JOIN table2;