用MySQL计数

Question

有没有办法在MySQL更新查询中计算Int？

目前我有

UPDATE mails SET uid = 4275

我想要像

这样的东西

UPDATE mails SET uid = (4275++)

Answer 1

你想做这样的事吗？

SELECT @i:=425;

UPDATE mails SET uid = @i:=@i+1;

Answer 2

如果您需要更新表格以便将每个uid增加1，那么您可以这样做：

   UPDATE mails 
   SET uid = uid + 1;

但是如果您需要将每个值uid增加一个增量值，请尝试：

SET @counter = 0; 
UPDATE mails m1
INNER JOIN
(
    SELECT *, (@counter := @counter +1) as counter
    FROM mails
) m2 ON m1.uid = m2.uid
SET m1.uid = m1.uid + m2.counter

如果您想从4275开始计算，只需将计数器设置为SET @counter = 4275

Answer 3

更新邮件SET uid = uid + x

x表示任何数字

我没有正确地回答您的问题，但我只是按照我的理解回答

更新邮件SET uid = uid + 1

即通过lastuid + 1增加当前uid

Answer 4

UPDATE mails SET uid = uid +1会在每个uid列中添加1。

Answer 5

尝试

UPDATE mails SET uid = uid+1
where uid = 4275

Answer 6

你可以保留自己的计数器

declare @curr_uid integer; 
SET @curr_uid = 4275; -- initial uid

update mails
set uid = @curr_uid , @curr_uid = @curr_uid + 1