sql – 多个FULL OUTER JOIN在多个表上

发布时间：2020-12-12 08:42:59 所属栏目：MsSql教程来源：网络整理

导读：我有多个外连接 SELECT A.column2,B.column2,C.column2FROM ( (SELECT month,column2 FROM table1) A FULL OUTER JOIN (SELECT month,column2 FROM table2) B on A.month= B.month FULL OUTER JOIN (SELECT month,column2 FROM table3) C on A.month= C.month

我有多个外连接

SELECT  A.column2,B.column2,C.column2
FROM 
(
    (SELECT month,column2 FROM table1) A
    FULL OUTER JOIN
    (SELECT month,column2 FROM table2) B on A.month= B.month
    FULL OUTER JOIN 
    (SELECT month,column2 FROM table3) C on A.month= C.month
)

现在最后一次加入是有问题的,当A的月份超过B时重复,但是如果B有更多的月份,那么我们在C中有了外部加载的A,而A的月份现在重复,所以我想在一个FULL OUTER JOIN两个表可能会解决问题？任何深入的链接？

样本数据(不正确)

╔════════════╦═════════╦═════════════╗
║  Revenue   ║ Budget  ║ ActualMonth ║
╠════════════╬═════════╬═════════════╣
║     6.9172 ║ 3.5046  ║ Jan         ║
║     7.3273 ║ 3.7383  ║ Feb         ║
║     7.3273 ║ 3.9719  ║ Mar         ║
║     7.2726 ║ 4.2056  ║ Apr         ║
║     7.2595 ║ 6.7757  ║ May         ║
║     7.2726 ║ 6.7757  ║ Jun         ║
║     0.41   ║ 0.00    ║ Jul         ║
║     0.41   ║ 0.00    ║ Aug         ║
║     0.41   ║ 0.00    ║ Sep         ║
║     0.41   ║ 0.00    ║ Oct         ║
║     7.4696 ║ 0.00    ║ Nov         ║
║     7.4696 ║ 0.00    ║ Dec         ║
║     0.00   ║ 9.3457  ║ Sep         ║
║     0.00   ║ 16.3551 ║ Dec         ║
║     0.00   ║ 6.3084  ║ Jul         ║
║     0.00   ║ 14.0186 ║ Oct         ║
║     0.00   ║ 16.3551 ║ Nov         ║
║     0.00   ║ 6.1915  ║ Aug         ║
╚════════════╩═════════╩═════════════╝

数据正确

╔════════════╦═════════╦═════════════╗
║  Revenue   ║ Budget  ║ ActualMonth ║
╠════════════╬═════════╬═════════════╣
║     6.9172 ║ 3.5046  ║ Jan         ║
║     7.3273 ║ 3.7383  ║ Feb         ║
║     7.3273 ║ 3.9719  ║ Mar         ║
║     7.2726 ║ 4.2056  ║ Apr         ║
║     7.2595 ║ 6.7757  ║ May         ║
║     7.2726 ║ 6.7757  ║ Jun         ║
║     0.41   ║ 6.3084  ║ Jul         ║
║     0.41   ║ 6.1915  ║ Aug         ║
║     0.41   ║ 9.3457  ║ Sep         ║
║     0.41   ║ 14.0186 ║ Oct         ║
║     7.4696 ║ 16.3551 ║ Nov         ║
║     7.4696 ║ 16.3551 ║ Dec         ║
╚════════════╩═════════╩═════════════╝

解决方法

SELECT  A.column2,column2 FROM table3) C on ISNULL(A.month,B.month) = C.month
)

（编辑：李大同）

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