where isdate(substring(NL,1,4)什么意思?
ka7iu 2010-08-06 01:52:49 update yl_olap.dbo.TB_DM_Medical_Record
set NL = '99990101'
where isdate(substring(NL,1,4)+'-'+substring(NL,5,2)+'-'+substring(NL,7,2))<>1 or LEN(NL)<>8
这里面where isdate(substring(NL,1,4)+'-'+substring(NL,5,2)+'-'+substring(NL,7,2))<>1 or LEN(NL)<>8
这句话什么意思啊?