如何对GROUP BY子句生成的COUNT（名称）执行WHERE？

Question

在SELECT语句中在GROUP BY之前处理WHERE。如何在COUNT（名称）的结果上使用WHERE？

我想要的是：

SELECT topic, COUNT(name) AS counter
FROM blah
GROUP BY name
WHERE counter <> 1

Answer 1

SELECT topic, COUNT(name) AS counter
FROM blah
GROUP BY topic
HAVING COUNT(name) <> 1

Answer 2

我认为你正在寻找有条款：

http://msdn.microsoft.com/en-us/library/ms180199.aspx

SELECT topic, COUNT(name) AS counter
FROM blah
GROUP BY topic
HAVING COUNT(name) <> 1

Answer 3

正如对方已经回答你需要一个人。

WHERE过滤所有联接后剩余的行

GROUP BY将行组合成组

HAVING过滤这些群组

不要担心在SELECT列表中重复COUNT（*）并且有，优化器足够智能以优化大多数数据库的这个