Question

我有要求，我需要比较单个表的两行，并选择具有不同值的列。

主键是姓名和状态。

示例数据：

Row1:  'Jack', 1, a, b, c, d, e, f
Row2:  'Jack', 2, a, b, x, d, y, f

所以我的要求是选择x和y。这里'杰克'是姓名，1,2是状态。

Answer 1

If the Columns are same 
SELECT a.col1,a.Col2 FROM (SELECT col1,Col2 FROM Table WHERE id=1 UNION SELECT col1,Col2 FROM Table WHERE id=2) a

另外我们也可以这样做

select t1.value,t2.value
from Table t1
    inner join Table t2 on
        t1.id = t2.id

Answer 2

我认为应该是这样的：

SELECT T1.*
FROM MainTable AS T1
INNER JOIN MainTable AS T2
    ON T1.Name = T2.Name
    AND T1.Status != T2.Status
    AND (T1.col1 != T2.col1
    OR T1.col2 != T2.col2
    OR T1.col3 != T2.col3)

您可以选择名称匹配且状态不匹配的匹配项，以及至少有一列不匹配的匹配项。

根据要求更新：如果您只想要列，那么最可读的是为每列创建单独的选择：

SELECT T2.col1
FROM MainTable AS T1
INNER JOIN MainTable AS T2
    ON T1.Name = T2.Name
    AND T1.Status != T2.Status
    AND T1.col1 != T2.col1
UNION ALL
SELECT T2.col2
FROM MainTable AS T1
INNER JOIN MainTable AS T2
    ON T1.Name = T2.Name
    AND T1.Status != T2.Status
    AND T1.col2 != T2.col2
UNION ALL
SELECT T2.col3
FROM MainTable AS T1
INNER JOIN MainTable AS T2
    ON T1.Name = T2.Name
    AND T1.Status != T2.Status
    AND T1.col3 != T2.col3
And so on....

如何比较单个表的两行？

2 个答案: