--显示sql server现有的所有数据库 exec sp_helpdb
--查看数据表设置的约束
exec sp_helpconstraint SubjectType
--update select出来的结果集的字段 update QuestionToAnswer set IsDel=1,Marker=15,MarkingTime=getdate() where ID in (select QTA.ID from QuestionToAnswer QTA --QTA.ID,QTA.StudentID,QTA.IsDel,QTA.Score inner join TClassStudent TCS on QTA.StudentID=TCS.StudentID and QTA.IsDel=0 and TCS.IsDel=0 where QTA.QuestionID=52 and TClassID=9)