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 A INNER JOIN Table_B B ON A.Key = B.Key 2.LEFT JOIN(左连接) SELECT FROM Table_A A LEFT JOIN Table_B B ON A.Key = B.Key 3.RIGHT JOIN(右连接) SELECT FROM Table_A A RIGHT JOIN Table_B B ON A.Key = B.Key 4.OUTER JOIN(外连接) SELECT FROM Table_A A FULL OUTER JOIN Table_B B ON A.Key = B.Key 5.LEFT JOIN EXCLUDING INNER JOIN(左连接-内连接) SELECT FROM Table_A A LEFT JOIN Table_B B ON A.Key = B.Key WHERE B.Key IS NULL 6.RIGHT JOIN EXCLUDING INNER JOIN(右连接-内连接) SELECT FROM Table_A A RIGHT JOIN Table_B B ON A.Key = B.Key WHERE A.Key IS NULL 7.OUTER JOIN EXCLUDING INNER JOIN(外连接-内连接) SELECT 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 |
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