sql语句记录

//将两个表连接起来
select yb.yxsh,yb.zgh,jzg.xm,sum(byjxjcs) as bnjxjcs,sum(byjxjje) as bnjezs,floor(avg(xsrs))
    from yb_jxjtjb yb left join jzgjbxxb jzg on yb.zgh=jzg.zgh
    where yb.yxsh='090000' and yb.tjnf='2011'
    group by yb.zgh,yb.yxsh,jzg.xm

部分更新数据

//有选择的更新数据
update sc
    set grade=0
    where 'cs'=(select sdept from student where student.sno=sc.sno)

//将一个表中的数据插入到另一个表中，并对部分数据进行修改
insert into yb_jxjtjb(yxsh,zgh,tjnf,tjyf)
    select yxsh,zgh,tjnf,tjyf-1
    from yb_jxjtjb
    where zgh='1111'