Question

表A

P         Q            R
1         A            a
2         B            a
3         C            b
4         D            b

如何将其转换为

表B

P         a            b
1         A            -
2         B            -
3         -            C
4         -            D

提示：a与A和B一起映射而不是表A中的C＆amp; D.类似地，b与C＆amp; D映射而不是A＆amp; B.枢轴不工作。请帮忙。

Answer 1

这可以使用Dynamic CrossTab实现。供参考：http://www.sqlservercentral.com/articles/Crosstab/65048/

示例数据

CREATE TABLE SampleData(
    P   INT,
    Q   CHAR(1),
    R   CHAR(1)
)
INSERT INTO SampleData
    SELECT 1, 'A', 'a' UNION ALL
    SELECT 2, 'B', 'a' UNION ALL
    SELECT 3, 'C', 'b' UNION ALL
    SELECT 4, 'D', 'b'

动态交叉表

DECLARE @sql1 VARCHAR(4000) = '',
        @sql2 VARCHAR(4000) = '',
        @sql3 VARCHAR(4000) = ''

SELECT @sql1 =
'SELECT
    P' + CHAR(10)

SELECT @sql2 = @sql2 +
'   ,MAX(CASE WHEN R = ''' + R + ''' THEN Q END) AS [' + R + ']' + CHAR(10)
FROM(
    SELECT DISTINCT R FROM SampleData
)t
ORDER BY R

SELECT @sql3 = 
'FROM SampleData
GROUP BY P
ORDER BY P
'

PRINT(@sql1 + @sql2 + @sql3)
EXEC(@sql1 + @sql2 + @sql3)

<强> RESULT

P           a    b
----------- ---- ----
1           A    NULL
2           B    NULL
3           NULL C
4           NULL D

Answer 2

试试这个

select P, 
case when R='a' then a else '-' end as a,
case when R='b' then '-' else a end as b
from table_A

如何将表值交换到sql中的列

2 个答案: