Question

我有一个选择查询

Select col1,col2,col3 
from table;

该表包含以下行

col1 col2 col3 
A    | B  | C
B    | A  | C
C    | B  | C

我需要通过比较多列来获得包含单个组合A，B，C的独特结果。

结果应该是像

这样的东西

col1 col2 col3 
A    | B  | C

可以更改结果行的顺序。

我怎样才能做到这一点？

Answer 1

请试试这个，我不确定你的正确要求。但是上面给出的样本数据。我遇到过这个解决方案，

With CTE as
(
     Select MIN(col1) as col1 from MyTable
)
Select * from CTE
cross apply
    (
        Select MIN(col2) as col2 from MyTable
        where col2 <> CTE.col1
    )as a
cross apply
    (
        Select MIN(col3) as col3 from MyTable
        where col3 not in (CTE.col1,a.col2)
    )as b

DEMO HERE

Answer 2

SELECT *
FROM table
WHERE (col1 = 'A' AND col2 = 'B' AND col3 = 'C')

Answer 3

如果列数和值已知，您也可以使用以下查询。

The CASE statement is the closest to IF in SQL

SELECT
         CASE 
              WHEN (col1 = 'A' and col2 = 'B' and col3='C') or (col1 = 'C' and col2 = 'A' and col3='B') or (col1 = 'B' and col2 = 'C' and col3='A' )
                 THEN 1 
              ELSE 0 
         END  as RESULT, * 
FROM table

从结果中，您可以通过检查RESULT==1(integer)

的值来获取所需的输出

如果您想要result as a boolean value，请执行CAST之类的

SELECT
     CAST(
         CASE 
              WHEN (col1 = 'A' and col2 = 'B' and col3='C') or (col1 = 'C' and col2 = 'A' and col3='B') or (col1 = 'B' and col2 = 'C' and col3='A' )
                 THEN 1 
              ELSE 0 
         END  as RESULT_INT)
     as RESUTL, * 
FROM table

通过比较多列SQL来区分

3 个答案: