sql查询问题

[huqin_1223]

有两张表:product和picture
product 中的字段：id....
picture 中的字段：id,proID（产品表中的id）,url
一个产品对应几张图片，
现在要查询中一个产品对应的一张图片要如何实现？？？

[冷箫轻笛]

--选择每个产品id最小的图片
select * from picture a
where not exists(select 1 from picture where proid = a.proid and id < a.id)

[pt1314917]

product 中的字段：id....
picture 中的字段：id,proID（产品表中的id）,url
一个产品对应几张图片，
现在要查询中一个产品对应的一张图片要如何实现？？？

select a.*,b.url from product a,picture b 
where a.id=b.proid and not exists(select 1 from picture where proid=b.proid and id>b.id)

[老宛]

select a.*,b.url from product a (select proID,min(url) as url from picture group by proId) b on a.id=b.ProID

[老宛]

select   a.*,b.url   from   product   a  left join (select   proID,min(url)   as   url   from   picture   group   by   proId)   b   on   a.id=b.ProID

[fjzz110]

拉完请冲水