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  • 3、SQL基础整理(分组)

    分组

    group by

    select class from xuesheng group by class

    select class,AVG(chinese)from xuesheng group by class

    select math from xuesheng where math >80 group by math

    select math from xuesheng where math between 80 and 90 group by math

    select math,count(*) from xuesheng where math between 80 and 90 group by math

    选出语文成绩>80的班级行总数,按班级分组

    select class,COUNT(*)from xuesheng where chinese>80 group by class

    having 后面只能加聚合函数(从表中选出where后,先看前面的聚合函数,再算后面的聚合函数)

    select class,COUNT(*)from xuesheng where chinese>=80 group by class having COUNT(*)>10

    select class,COUNT(*),AVG(math)from xuesheng group by class having AVG(math)>90

    select class,COUNT(*) from xuesheng where math>80 group by class order by COUNT(*)

    --分别求每个班语数外最高分,并按语文升序排序

    select class,MAX(chinese),MAX(math),MAX(english) from xuesheng group by class order by MAX(chinese)

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  • 原文地址:https://www.cnblogs.com/wleaves/p/4164981.html
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