Question

我正在尝试使用以下查询更新子查询返回的某些行上的列。子查询选择需要更新的行的右侧ID。

UPDATE 4_dev.Images AS Im
        SET Im.primary=1 
        WHERE EXISTS (
SELECT Img.imageId FROM (
SELECT I.id AS imageId,
       I.userId,
       I.date,
       SUM(I.primary) AS hasPrimary,
       COUNT(*) AS numImages
FROM 4_dev.Images AS I
GROUP BY I.userId
HAVING numImages>=1 AND hasPrimary=0) AS Img)

但是这个查询会更新每一行，而不仅仅是SELECT子查询中的行。

这很容易在PHP中分成两部分，但我想知道如何用一个查询更新它。感谢。

Answer 1

更改WHERE EXISTS ( 到WHERE Im.id IN (

Answer 2

您的查询中有错误，您忘记在尝试更新的表和EXISTS中的语句之间定义连接条件

UPDATE 4_dev.Images AS Im
  SET Im.primary=1 
WHERE EXISTS (
  SELECT Img.imageId
  FROM (
    SELECT I.id AS imageId,
      I.userId,
      I.date,
      SUM(I.primary) AS hasPrimary,
      COUNT(*) AS numImages
    FROM 4_dev.Images AS I
    GROUP BY I.userId
    HAVING numImages>=1 AND hasPrimary=0) AS Img
    WHERE Img.imageId = Im.id)

此外，您的查询很复杂。遗憾的是，我不知道您的数据库结构，但看起来您可以使用多个表中的UPDATE来简化查询 http://forums.mysql.com/read.php?20,85813,85813

如何根据select语句更新行

2 个答案: