SQL笔记

多表联合查询:
     例句1:select a.ypbh,a.ypmc,b.ghsbh,c.khbh,c.khmc from ((ypdm a inner join ghskcbs b on b.ypbh=a.ypbh) inner join ghsdm c on c.khbh=b.ghsbh)
     例句2:select a.ypbh,a.cdbh,a.ypmc,b.ghsbh,c.khbh,c.khmc,d.cdmc from (((ypdm a inner join ghskcbs b on b.ypbh=a.ypbh) inner join ghsdm c on c.khbh=b.ghsbh) inner join cddm d on d.cdbh=a.cdbh)
     技巧:from之后的每一个inner join子名都用括号层层包裹起来.


自增长字段重置(删除数据并重置自增长字段为1)
delete from UserInfo
DBCC CHECKIDENT (UserInfo,RESEED,0)