一张图看懂SQL的各种Join用法,
下图展示了 LEFT JOIN、RIGHT JOIN、INNER JOIN、OUTER JOIN 相关的 7 种用法。
具体分解如下:
1、INNER JOIN(内连接)
- SELECT FROM Table_A AINNER JOIN Table_B BON A.Key = B.Key
2、LEFT JOIN(左连接)
- SELECT FROM Table_A ALEFT JOIN Table_B BON A.Key = B.Key
3、RIGHT JOIN(右连接)
- SELECT FROM Table_A ARIGHT JOIN Table_B BON A.Key = B.Key
4、OUTER JOIN(外连接)
- SELECT FROM Table_A AFULL OUTER JOIN Table_B BON A.Key = B.Key
5、LEFT JOIN EXCLUDING INNER JOIN(左连接-内连接)
- SELECT FROM Table_A ALEFT JOIN Table_B BON A.Key = B.KeyWHERE B.Key IS NULL
6.RIGHT JOIN EXCLUDING INNER JOIN(右连接-内连接)
- SELECT FROM Table_A ARIGHT JOIN Table_B BON A.Key = B.KeyWHERE A.Key IS NULL
7、OUTER JOIN EXCLUDING INNER JOIN(外连接-内连接)
- SELECT FROM Table_A AFULL OUTER JOIN Table_B BON A.Key = B.KeyWHERE A.Key IS NULL OR B.Key IS NULL
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