给定tblAllKeys(fldKey, fldCode)
并tblModKeys(fldKey, fldCode)
具有tblAllKeys
...的数据
fldCode fldKey
dba 1
dba 2
dba 3
dba 4
cde 1
cde 2
cde 3
在tblModKeys
...
fldCode fldKey
dba 1
dba 2
dba 3
dba 4
dba 5
dba 6
cde 1
cde 2
cde 3
cde 4
我想从tblModKeys返回行,其中fldCode与tblAllKeys.fldCode相匹配,但tblAllKeys.fldCode中不存在tblModKeys.fldKey。我有兴趣知道是否有一种方法专门用于联接吗?
SELECT DISTINCT mk.*
FROM tblModkeys mk
JOIN tblAllkeys ak1 ON mk.fldcode = ak1.fldcode -- fldcode exists in tblAllkeys
LEFT JOIN tblAllkeys ak2 ON mk.fldkey = ak2.fldkey
WHERE ak2.fldkey IS NULL -- fldkey does not exist in tblAllkeys
本文收集自互联网,转载请注明来源。
如有侵权,请联系 [email protected] 删除。
我来说两句