select * from a
where len(Convert(nvarchar(50),atime))=19 and charindex('-',Convert(nvarchar(50),atime))=5 and charindex(' ',Convert(nvarchar(50),atime))=11 and charindex(':',Convert(nvarchar(50),atime))=14
and substring (Convert(nvarchar(50),atime),6,2)<=12
这样试试