如何在没有UNIQUE索引或PRIMARY KEY的MySQL中使用ON DUPLICATE KEY UPDATE？ [英] How to use ON DUPLICATE KEY UPDATE in MySQL without a UNIQUE index or PRIMARY KEY?

问题描述

MySQL手册指出：

The MySQL manual states:

如果指定ON DUPLICATE KEY UPDATE，并插入一行
将导致UNIQUE索引中的重复值或PRIMARY KEY

If you specify ON DUPLICATE KEY UPDATE, and a row is inserted that would cause a duplicate value in a UNIQUE index or PRIMARY KEY

如果您的表没有UNIQUE索引或PRIMARY KEY，该怎么办？但你不想复制一个列的条目（比如user_id）。

What if you have a table that does not have a UNIQUE index or PRIMARY KEY, but you don't want to duplicate an entry for a column (say user_id).

有没有办法在MySQL中做到这一点？

Is there a way to do it in MySQL?

推荐答案

INSERT INTO `table` (value1, value2) 
SELECT 'stuff for value1', 'stuff for value2' FROM `table` 
WHERE NOT EXISTS (SELECT * FROM `table` 
                  WHERE value1='stuff for value1' AND value2='stuff for value2') 
LIMIT 1

资料来源：如何在MySQL中'插入，如果不存在'？

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