select miss.mname as '小姐',maid.dname as '丫环' from miss
left join md on miss.mno=md.mno
left join maid on md.dno=maid.dno
order by miss.mname
select distinct miss.mname as '小姐' from miss
left join md on miss.mno=md.mno
left join maid on md.dno=maid.dno
where maid.dbeauty<85
select avg(dbeauty) as '平均美貌指数' from maid
select distinct miss.mname as '小姐' from miss
left join md on miss.mno=md.mno
left join maid on md.dno=maid.dno
where maid.dbeauty>(select avg(dbeauty) as '平均美貌指数' from maid)
select distinct t.mname from (
select miss.mname,count(maid.mno) as dy2 from miss
left join md on miss.mno=md.mno
left join maid on md.dno=maid.dno
group by miss.mname) t
where t.dy2>2
真是闲的蛋痛。。。我去
1.select a.dname,b.mname from maid a
inner join miss b on c.mno=b.mno
inner join md c on a.dno=c.dno
2.select a.manme,b.dname from miss a
inner join maid b on c.dno=b.dno
inner join md c on a.mno=c.mno
where b.dbeauty<85
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