WHERE子句中的MySQL用户定义变量 [英] MySQL user-defined variable in WHERE clause

问题描述

我想知道是否有一种方法可以在WHERE子句中使用用户定义的变量，如本例所示:

I want to know if there is a way to use a user-defined variable in WHERE clause, as in this example:

SELECT id, location, @id := 10 FROM songs WHERE id = @id

此查询运行没有错误，但没有按预期运行.

This query runs with no errors but doesn't work as expected.

推荐答案

与Mike E.提出的建议相距不远，但有一条声明:

Not far from what Mike E. proposed, but one statement:

SELECT id, location FROM songs, ( SELECT @id := 10 ) AS var WHERE id = @id;

我使用类似的查询来模拟MySQL中的窗口函数.例如. 行采样-只是在同一条语句中使用变量的示例

I used similar queries to emulate window functions in MySQL. E.g. Row sampling - just an example of using variables in the same statement

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