如何在MySQL中增加计数器并返回值 [英] How to increment a counter and return the value in MySQL

问题描述

我有一个包含Key列和Counter列的表.我需要做这样的事情:

I have a table that has a Key column and a Counter column. I need to do something like this:

SELECT counter=counter+1 FROM table WHERE key='mykey'

基本上，我需要增加Counter列并返回新值.如何在MySQL 5.5中做到这一点?

Basically, I need to increment the Counter column and return the new value. How can I do this in MySQL 5.5?

推荐答案

update mytable set count=last_insert_id(counter+1) where key='mykey'

然后

select last_insert_id()

可以向

last_insert_id()传递参数以对其进行设置"(并返回该值)，并且不带参数调用该参数将再次返回该值. last_insert_id()使用的内部状态是每个连接，这意味着在另一个连接上发出的同一update语句不会影响第一个连接.

last_insert_id() can be passed an argument to 'set' it (and return that value), and calling it without an argument will return the value again. The internal state used by last_insert_id() is per-connection, which means that the same update statement issued on another connection will not affect the first.

参考: last_insert_id()

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