表1
cCstId cCstName cParentId
01001 AAA 01001
01002 bbbbbb 01002
01003 CCCC 01003
11001 1AAAA 01001
11002 1BBBBB 01002
21001 2AAAA 01001
求一语句，得到以下结果
cParentId cParentName cCstId cCstName
01001 AAA 01001 AAA
01002 bbbbbb 01002 bbbbbb
01003 CCCC 01003 CCCC
01001 AAA 11001 1AAAA
01002 bbbbbb 11002 1BBBBB
01001 AAA 21001 2AAAA
------解决思路----------------------
直接连接就出来了
SELECT T1.cParentId,T2.cCstName AS cParentName,T1.cCstId,T1.cCstName FROM 表1 T1
JOIN 表1 T2 ON T1.cParentId=T2.cCstId
------解决思路----------------------
select cParentId,(select cCstName from 表1 where cCstId=a.cParentId) as cParentName ,cCstId,cCstName from 表1 as a