我知道你可以一次插入多行，是否有一种方法可以一次更新多行(如在，在一个查询)在MySQL?
编辑: 例如，我有以下内容
Name id Col1 Col2
Row1 1 6 1
Row2 2 2 3
Row3 3 9 5
Row4 4 16 8
我想将以下所有更新组合成一个查询
UPDATE table SET Col1 = 1 WHERE id = 1;
UPDATE table SET Col1 = 2 WHERE id = 2;
UPDATE table SET Col2 = 3 WHERE id = 3;
UPDATE table SET Col1 = 10 WHERE id = 4;
UPDATE table SET Col2 = 12 WHERE id = 4;
当前回答
这个问题很老了，但我想用另一个答案来扩展这个话题。
我的观点是，实现它的最简单的方法是用一个事务包装多个查询。这句话的意思是:ON DUPLICATE KEY UPDATE是一个很好的黑客，但人们应该意识到它的缺点和限制:
As being said, if you happen to launch the query with rows whose primary keys don't exist in the table, the query inserts new "half-baked" records. Probably it's not what you want If you have a table with a not null field without default value and don't want to touch this field in the query, you'll get "Field 'fieldname' doesn't have a default value" MySQL warning even if you don't insert a single row at all. It will get you into trouble, if you decide to be strict and turn mysql warnings into runtime exceptions in your app.
I made some performance tests for three of suggested variants, including the INSERT ... ON DUPLICATE KEY UPDATE variant, a variant with "case / when / then" clause and a naive approach with transaction. You may get the python code and results here. The overall conclusion is that the variant with case statement turns out to be twice as fast as two other variants, but it's quite hard to write correct and injection-safe code for it, so I personally stick to the simplest approach: using transactions.
编辑:Dakusan的发现证明我的性能估计不太有效。请参阅另一个更详细的研究的答案。
其他回答
UPDATE table1, table2 SET table1.col1='value', table2.col1='value' WHERE table1.col3='567' AND table2.col6='567'
这应该对你有用。
MySQL手册中有关于多个表的参考。
UPDATE tableName SET col1='000' WHERE id='3' OR id='5'
这应该能达到你想要的效果。只需要添加更多的id。我已经测试过了。
还没有人提到对我来说更简单的方法——使用SQL编辑器，允许你执行多个单独的查询。这张截图来自Sequel Ace，我认为Sequel Pro和其他编辑器可能有类似的功能。(当然，这是假设你只需要一次性运行它，而不是作为应用程序/网站的集成部分)。
由于您有动态值，因此需要为要更新的列使用IF或CASE。虽然有点难看，但应该能行。
用你的例子，你可以这样做:
UPDATE table SET Col1 = CASE id
WHEN 1 THEN 1
WHEN 2 THEN 2
WHEN 4 THEN 10
ELSE Col1
END,
Col2 = CASE id
WHEN 3 THEN 3
WHEN 4 THEN 12
ELSE Col2
END
WHERE id IN (1, 2, 3, 4);
您可能还对在更新上使用连接感兴趣，这也是可能的。
Update someTable Set someValue = 4 From someTable s Inner Join anotherTable a on s.id = a.id Where a.id = 4
-- Only updates someValue in someTable who has a foreign key on anotherTable with a value of 4.
编辑:如果要更新的值不是来自数据库中的其他地方，则需要发出多个更新查询。
