SQL Server中Group By、Having和Where子句的执行顺序? [英] Execution sequence of Group By, Having and Where clause in SQL Server?

问题描述

当我们使用带有 WHERE 子句的 GROUP BY 和 HAVING 时，我只是对 SQL 查询的执行顺序感到困惑.哪个先执行?顺序是什么?

I am just confused with the execution sequence of a SQL query when we use GROUP BY and HAVING with a WHERE clause. Which one gets executed first? What is the sequence?

推荐答案

按顺序:

来自 &JOINs 决定 &过滤行
WHERE 行上的更多过滤器
GROUP BY 将这些行组合成组
HAVING 过滤器组
ORDER BY 排列剩余的行/组
LIMIT 过滤剩余的行/组

FROM & JOINs determine & filter rows
WHERE more filters on the rows
GROUP BY combines those rows into groups
HAVING filters groups
ORDER BY arranges the remaining rows/groups
LIMIT filters on the remaining rows/groups

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