mysql列(时间戳)也会自动更新为系统当前时间

Question

为什么当我更新一列时另一列(时间戳)也自动更新为系统当前时间

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  ; 

试试这个查询:-

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

Remove on update CURRENT_TIMESTAMP