随笔分类 -  SQL Server

摘要：SELECT TOP 5 * FROM Users WHERE NOT EXISTS(SELECT * FROM (SELECT TOP 10 UserId FROM Users order by CreateDate desc )P WHERE P.UserId=Users.UserId) order by CreateDate DESC 阅读全文

摘要：NOT INSELECT DISTINCT MD001 FROM BOMMD WHERE MD001 NOT IN (SELECT MC001 FROM BOMMC)NOT EXISTS,exists的用法跟in不一样，一般都需要和子表进行关联，而且关联时，需要用索引，这样就可以加快速度select DISTINCT MD001 from BOMMD WHERE NOT EXISTS (SELECT MC001 FROM BOMMC where BOMMC.MC001 = BOMMD.MD001)exists是用来判断是否存在的，当exists(查询)中的查询存在结果时则返回真，否则返回假。n 阅读全文