请用关系代数表示下列查询语句F(drinker,bar) S (bar,beer) L (drinker,beer)1、找出这样的饮酒人,他经常光顾供应他喜欢的啤酒的酒吧间.2、找出不提供青岛啤酒的酒吧.3、找出这样的饮酒人,不去提
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![请用关系代数表示下列查询语句F(drinker,bar) S (bar,beer) L (drinker,beer)1、找出这样的饮酒人,他经常光顾供应他喜欢的啤酒的酒吧间.2、找出不提供青岛啤酒的酒吧.3、找出这样的饮酒人,不去提](/uploads/image/z/8549449-25-9.jpg?t=%E8%AF%B7%E7%94%A8%E5%85%B3%E7%B3%BB%E4%BB%A3%E6%95%B0%E8%A1%A8%E7%A4%BA%E4%B8%8B%E5%88%97%E6%9F%A5%E8%AF%A2%E8%AF%AD%E5%8F%A5F%EF%BC%88drinker%2Cbar%EF%BC%89+S+%28bar%2Cbeer%29+L+%28drinker%2Cbeer%291%E3%80%81%E6%89%BE%E5%87%BA%E8%BF%99%E6%A0%B7%E7%9A%84%E9%A5%AE%E9%85%92%E4%BA%BA%2C%E4%BB%96%E7%BB%8F%E5%B8%B8%E5%85%89%E9%A1%BE%E4%BE%9B%E5%BA%94%E4%BB%96%E5%96%9C%E6%AC%A2%E7%9A%84%E5%95%A4%E9%85%92%E7%9A%84%E9%85%92%E5%90%A7%E9%97%B4.2%E3%80%81%E6%89%BE%E5%87%BA%E4%B8%8D%E6%8F%90%E4%BE%9B%E9%9D%92%E5%B2%9B%E5%95%A4%E9%85%92%E7%9A%84%E9%85%92%E5%90%A7.3%E3%80%81%E6%89%BE%E5%87%BA%E8%BF%99%E6%A0%B7%E7%9A%84%E9%A5%AE%E9%85%92%E4%BA%BA%2C%E4%B8%8D%E5%8E%BB%E6%8F%90)
请用关系代数表示下列查询语句F(drinker,bar) S (bar,beer) L (drinker,beer)1、找出这样的饮酒人,他经常光顾供应他喜欢的啤酒的酒吧间.2、找出不提供青岛啤酒的酒吧.3、找出这样的饮酒人,不去提
请用关系代数表示下列查询语句
F(drinker,bar) S (bar,beer) L (drinker,beer)
1、找出这样的饮酒人,他经常光顾供应他喜欢的啤酒的酒吧间.
2、找出不提供青岛啤酒的酒吧.
3、找出这样的饮酒人,不去提供雪花啤酒的酒吧的.
4、找出这样的饮酒人,他和另一个喜欢‘青岛’啤酒的人在同一酒吧.
请用关系代数表示下列查询语句F(drinker,bar) S (bar,beer) L (drinker,beer)1、找出这样的饮酒人,他经常光顾供应他喜欢的啤酒的酒吧间.2、找出不提供青岛啤酒的酒吧.3、找出这样的饮酒人,不去提
1
select c.bar,a.drinker,c.beer from f as a,s as b,l as c where b.bar=a.bar and a.drinker=c.drinker group by c.bar,a.drinker,c.beer having max(count(*))
[原理,将三个关系表联系起来,分组统计出酒吧,人,啤酒的统计信息,在找出最大行数的列]
2
select bar from s where not beer='青岛啤酒'
3
select drinker from f where drinker not in (select a.drinker from f as a,s as b where a.bar=b.bar and b.beer='雪花啤酒')
[原理:查询出去了提供雪花啤酒的酒家的人,再not in排除掉]
4
select a.drinker,a.bar from f as a,s as b where a.bar=b.bar where b.beer='青岛啤酒' group by a.drinker,a.bar having Count(*)>1