下图展示了 LEFT JOIN、RIGHT JOIN、INNER JOIN、OUTER JOIN 相关的 7 种用法。
- SELECT <select_list>
- FROM Table_A A
- INNER JOIN Table_B B
- ON A.Key = B.Key
- SELECT <select_list>
- FROM Table_A A
- LEFT JOIN Table_B B
- ON A.Key = B.Key
- SELECT <select_list>
- FROM Table_A A
- RIGHT JOIN Table_B B
- ON A.Key = B.Key
- SELECT <select_list>
- FROM Table_A A
- FULL OUTER JOIN Table_B B
- ON A.Key = B.Key
- SELECT <select_list>
- FROM Table_A A
- LEFT JOIN Table_B B
- ON A.Key = B.Key
- WHERE B.Key IS NULL
- SELECT <select_list>
- FROM Table_A A
- RIGHT JOIN Table_B B
- ON A.Key = B.Key
- WHERE A.Key IS NULL
- SELECT <select_list>
- FROM Table_A A
- FULL OUTER JOIN Table_B B
- ON A.Key = B.Key
- WHERE A.Key IS NULL OR B.Key IS NULL