没有唯一列的MySQL'DUPLICATE KEY更新'? [英] MySQL 'UPDATE ON DUPLICATE KEY' without a unique column?

问题描述

人们对执行以下查询的最高效的方式有何看法:

What are peoples' thoughts on the most performance efficient way to do the following query:

• 3列表

• 3 column table

，如果col_1和col_2值的组合已经存在UPDATE col_3

if the combination of col_1 and col_2 values already exist UPDATE col_3

其他INSERT新行

我假设我需要某种对UP DUMPLICATE KEY的更新(我以前从未使用过)，但是我没有一个"KEY"，而是一对两个值(列)来构成一个钥匙...

I assume i need some kind if UPDATE ON DUPLICATE KEY (which i've never used before), however I do not have a 'KEY' but instead a pair of two values (columns) to make a key...

推荐答案

您可以在MySQL中的多个列中创建一个PRIMARY或UNIQUE键(称为复合键)，这将允许ON DUPLICATE KEY工作正常.

You can create a PRIMARY or UNIQUE key out of multiple columns (called a composite key) in MySQL, which'll allow ON DUPLICATE KEY to work just fine.

// create a composite index
CREATE INDEX my_composite_index ON my_table (column1, column2);

// insert or update
INSERT INTO my_table (column1, column2) VALUES ('value1', 'value2') ON DUPLICATE KEY UPDATE column3=column3+1;

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