我可以在LIMIT偏移量中使用MySQL函数吗 [英] Can I use MySQL functions in the LIMIT offset

问题描述

我可以在LIMIT偏移中使用MySQL函数吗? 喜欢:

Can I use MySQL functions in the LIMIT offset? Like:

SELECT * FROM sites WHERE ... LIMIT FLOOR(1 + RAND() * (SELECT COUNT(*) FROM sites)) , 1

推荐答案

不，您不能直接这样做. LIMIT和OFFSET值必须是常量.

No, you can't do that directly. LIMIT and OFFSET values must be constants.

MySQL文档的引用:

LIMIT子句可用于约束SELECT语句返回的行数. LIMIT接受一个或两个数字参数，这两个参数都必须是非负的整数常量(使用预处理语句时除外).

The LIMIT clause can be used to constrain the number of rows returned by the SELECT statement. LIMIT takes one or two numeric arguments, which must both be nonnegative integer constants (except when using prepared statements).

不过，您可以使用准备好的语句和变量:

You can use prepared statements and variables, though:

SELECT @offset:=FLOOR(1 + RAND() * COUNT(*)) FROM sites;
PREPARE STMT FROM 'SELECT * FROM sites WHERE ... LIMIT ?, 1';
EXECUTE STMT USING @offset; 

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