SQL-WHERE AGGREGATE> 1 [英] SQL - WHERE AGGREGATE>1

问题描述

想象一下，我有一个客户数据库表，其中包含{id，username，firstname，lastname}

Imagine I have a db table of Customers containing {id,username,firstname,lastname}

如果我想查找多少个具有不同名字的实例，可以这样做：

If I want to find how many instances there are of different firstnames I can do:

select firstname,count(*) from Customers group by 2 order by 1;

   username | count(*)
   ===================
   bob      |   1
   jeff     |   2
   adam     |   5

我如何编写相同的查询以仅返回多次出现的名字？例如，在上面的示例中，仅返回jeff和adam的行。

How do I write the same query to only return firstnames that occur more than once? i.e. in the above example only return the rows for jeff and adam.

推荐答案

您希望具有子句，像这样：

select 
    firstname,
    count(*) 
from Customers 
group by firstname
having count(*) > 1
order by 1

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