在子查询中使用SQL_CALC_FOUND_ROWS [英] Using SQL_CALC_FOUND_ROWS in a subquery

问题描述

我发现MySQL返回一个

I find that MySQL returns a

Incorrect usage/placement of 'SQL_CALC_FOUND_ROWS'

如果我将SQL_CALC_FOUND_ROWS放在子查询中，则会出错

error if I put SQL_CALC_FOUND_ROWS in a subquery

SELECT
  *
FROM
  (
     SELECT SQL_CALC_FOUND_ROWS * FROM test_table
  ) as T1

是否有解决方法?还是我实施不正确?

Is there a workaround for this? or am I just implementing it incorrectly?

如果有人想知道的话，我有必要将T1设为子查询是有原因的.

There is a reason why I need to make T1 a subquery in case anyone is wondering.

推荐答案

似乎您使用的方式不正确. SQL_CALC_ROWS_FOUND似乎仅适用于外部查询.我不确定这是否适合您的用例，或者您的外部查询中是否包含其他WHERE，但是您可以执行以下操作:

It seems like you're using it incorrectly. The SQL_CALC_ROWS_FOUND seems to only apply to outer queries. I'm not sure if this would fit your use case, or if you have additional WHEREs in your outer query, but you may be able to do something like this:

选择 SQL_CALC_FOUND_ROWS * 从 ( SELECT * FROM test_table )作为T1;
SELECT FOUND_ROWS();

SELECT SQL_CALC_FOUND_ROWS * FROM ( SELECT * FROM test_table ) as T1 ;
SELECT FOUND_ROWS();

FOUND_ROWS()函数将为您提供在应用任何LIMIT之前找到的总行数.有关FOUND_ROWS()的更多信息，请在此处.

The FOUND_ROWS() function will give you the total number of rows found before any LIMITs are applied. For more on FOUND_ROWS() check here.

这篇关于在子查询中使用SQL_CALC_FOUND_ROWS的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！