Mysql 如何基于select语句更新行
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正确IDMysql 如何基于select语句更新行,mysql,sql,Mysql,Sql,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正确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(
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
这在PHP中很容易分成两部分,但我想知道如何用一个查询来更新它。谢谢。更改存在的位置(
若要
在Im.id所在的位置(
您的查询有错误,您忘记了在您尝试更新的表和存在的语句之间定义联接条件
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。
不幸的是,我不知道您的数据库结构,但看起来您可以使用多个表的更新简化查询