使用SQL语言的SELECT语句进行分组查询时，如果希望去掉不满足条件的分组，应当使用( ? )子句 使用sql语句进行分组查询时为了去掉不满足条件组应该
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Hope I can help you
select a,sum(qty) from table where c='t' group by a having sum(qty)>10
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group by ....
where ...
having ...
对于能够直接判断的，用where就可以排除
对于使用聚和函数产生的值，需要在having中判断例如
where 成绩 > 90
having avg(成绩) > 90
where 和 having 可以同时使用
where
having
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