Question

我有一个表 - 它就像几个表连接在一起，因为[Col1]接受两个不同的字符串，[Value]接受与[Col1]字符串相关的数值。分段有2组列。分析每个细分和稍后的细分组合。日期戳也可用。

Col1   datestamp Value
ret     1/10/14
ent     1/10/14
ret     2/1/14
ent     2/1/14

完成的表格如下所示：

Col1ret  Col2ent  datestamp Value-ret Value-ent
ret       ent     1/10/14
ret       ent     2/1/14

执行此操作的SQL脚本是什么？

Answer 1

您可以使用PIVOT TABLE转换您的查询结果

CREATE TABLE #tmp (col1 nvarchar(5),datestamp DATETIME ,value int)

INSERT INTO #tmp VALUES ('ret',CAST('2014-10-01' AS DATE),null)
INSERT INTO #tmp VALUES ('ent',CAST('2014-10-01' AS DATE),null)
INSERT INTO #tmp VALUES ('ret',CAST('2014-2-1' AS DATE),null)
INSERT INTO #tmp VALUES ('ent',CAST('2014-2-1' AS DATE),null)

SELECT pv.ret
    ,pv.ent
    ,pv.datestamp
    ,pv.value
FROM (
    SELECT t.col1
        ,t.datestamp
        ,t.value
    FROM #tmp t
) as a
PIVOT (
    MAX(col1)
    FOR [col1] IN ([ret],[ent])
) as pv

DROP TABLE #tmp

你会得到像这样的查询结果

    ret ent datestamp               value
-------------------------------------
    ret ent 2014-02-01 00:00:00.000 NULL
    ret ent 2014-10-01 00:00:00.000 NULL

更多信息请参阅以下链接 https://technet.microsoft.com/en-us/library/ms177410%28v=sql.105%29.aspx

Answer 2

只需做一个简单的JOIN：

select t1.Col1 as Col1ret, t2.Col1 as Col2ent, t1.datestamp, t1.value as value-ret, t2.value as value-ent
from tablename t1
  join tablename t2 on t1.datestamp = t2.datestamp
where t1.Col1 = 'ret'
  and t2.Col1 = 'ent'

因为它的MySQL也许你需要替换＆＃34;背叛？

如何在sql中自己加入表？

2 个答案: