如何在UPDATE语句中联接两个表? [英] How to join two tables in an UPDATE statement?

问题描述

请考虑以下表格:用户"和推文"

Consider the following tables: "users" and "tweets"

user_id name             tweet_id user_id tweet        spam
-----------------        ----------------------------------
1       SUSPENDED        1        1       lorem ipsum  0
2       foo              2        1       dolor        0
3       bar              3        2       samet        0
4       SUSPENDED        4        1       stunitas     0
                         5        3       hello        0
                         6        4       spamzz!      0

我想通过将暂停"用户所做的所有推文标记为垃圾邮件来更新推文"表.因此，在上述示例中，通过将垃圾邮件"值从0更新为1，将tweet_id为1、2、4和6的tweet标记为垃圾邮件.

I want to update the "tweets" table by marking all tweets made by SUSPENDED users, as spam. So in the above example, tweets with tweet_id 1, 2, 4 and 6 would be marked as spam by updating the "spam" value from 0 to 1.

我无法连接两个表.到目前为止，我只需要加入SELECT语句，但这似乎更加麻烦:

I'm having trouble joining the two tables. Until now, I've only had to join in SELECT statements, but this seems more troublesome:

UPDATE tweets SET spam = 1 WHERE tweets.user_id = users.user_id 
AND users.name = 'SUSPENDED'

这肯定行不通...谁能向我指出正确的方向?

This surely isn't working...who could point me in the right direction?

推荐答案

您在正确的轨道上，但是需要在表之间指定JOIN:

You're on the right track, but you need to specify a JOIN between the tables:

UPDATE tweets JOIN users ON tweets.user_id = users.user_id
  SET tweets.spam = 1
WHERE users.name = 'SUSPENDED'

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