mysql列（timestamp）也会随系统当前时间自动更新

Question

为什么我更新一列但另一列（时间戳）也会自动更新系统当前时间

数据库mysql：

我执行的示例sql语句

select id, processstatus, processtimestamp from mytable where id=229;

id        processstatus                                                                                        processtimestamp          
--------- ---------------------------------------------------------------------------------------------------- ------------------------- 
229       EXPORT_FILEA.txt                                                                                     2015-11-04 12:54:49.0  





update  mytable set processstatus='EXPORT_TO_FILE_B' where id=229;

select id, processstatus, processtimestamp from mytable where id=229;

id        processstatus                                                                                        processtimestamp          
--------- ---------------------------------------------------------------------------------------------------- ------------------------- 
229       EXPORT_TO_FILE_B                                                                                     2015-11-04 13:09:41.0     

Answer 1

您可以像这样创建CURRENT_TIMESTAMP列： -

ALTER TABLE `table`  ADD `col_name` DATETIME 
on update CURRENT_TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP  ; 

尝试此查询： -

ALTER TABLE `table` CHANGE `col_name` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP;

  

删除on update CURRENT_TIMESTAMP