smelly_pretty 2011-11-17 14:10
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求解马士兵视频里关于数据库sql语句的笔试题

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  • _1_1_7_ 2011-11-17 15:01
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    [code="sql"]
    select * from
    (select a.productname,rednum-bluenum as diffnum
    from (select productname,sum(num) as rednum from product where color='红色' group by productname) as a,
    (select productname,sum(num) as bluenum from product where color='蓝色' group by productname) as b
    where a.productname=b.productname) where diffnum>0

    select a.productname as 产品,rednum as 红色,bluenum as 蓝色
    from (select productname,sum(num) as rednum from product where color='红色' group by productname) as a,
    (select productname,sum(num) as bluenum from product where color='蓝色' group by productname) as b
    where a.productname=b.productname[/code]

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