having——至少被订购过两回的订单

此篇介绍having的用法

一、表：订单表，产品表

说明：订单表order ,包含prodectid

二、查询至少被订购过两回的订单

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productid

SQL：

select prodectid from orders group by prodectid having count(prodectid)>1

分析：此查询需进行分组统计，需要group by +聚合函数count，因为有个条件“至少被订购两回”，可利用having

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至少被订购过两回

Normal
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7.8 磅
0
2

false
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EN-US
ZH-CN
X-NONE

MicrosoftInternetExplorer4

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