获取具有不同条件的同一列的总和

Question

我正在努力减轻查询的负担，并尝试通过优化查询来最大程度地减少查询量，因此我想将两个查询合二为一。

SELECT SUM(iAmount) as `shares`,
       (SELECT SUM(iAmount)
          FROM `investments`
         WHERE `iUser = 1
           AND DATE(`iTime`) = CURDATE()) as `shares_today`
  FROM `investments` WHERE `iUser` = 1

这不起作用，我做错了什么？

Answer 1

您在 iUser 之后缺少反引号。

但无论如何，这里不需要子查询：

SELECT SUM(`iAmount`) as `shares`,
       SUM(IF(DATE(`iTime`) = CURDATE(), `iAmount`, 0)) as `shares_today`
  FROM `investments`
 WHERE `iUser` = 1;

获取具有不同条件的同一列的总和

Get sum of same column with different conditiong

mysql

optimization

performance