[转载]MYSQL中TIMESTAMP类型的默认值

时间:2022-06-01 02:00:09

[转载]MYSQL中TIMESTAMP类型的默认值
 
 
MYSQL中TIMESTAMP类型可以设定默认值,就像其他类型一样。
1、自动UPDATE 和INSERT 到当前的时间:
表:
/*DDL Information For - test.t1*/
---------------------------------

Table   Create Table                                                                         
------  -------------------------------------------------------------------------------------
t1      CREATE TABLE `t1` (                                                                  
          `p_c` int(11) NOT NULL,                                                            
          `p_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP  
        ) ENGINE=InnoDB DEFAULT CHARSET=gb2312                                               


数据:

1    2007-10-08 11:53:35
2    2007-10-08 11:54:00

insert into t1(p_c) select 3;
update t1 set p_c = 2 where p_c = 2;

数据:

1    2007-10-08 11:53:35
2    2007-10-08 12:00:37
3    2007-10-08 12:00:37

2、自动INSERT 到当前时间,不过不自动UPDATE。

表:
/*DDL Information For - test.t1*/
---------------------------------

Table   Create Table                                             
------  ---------------------------------------------------------
t1      CREATE TABLE `t1` (                                      
          `p_c` int(11) NOT NULL,                                
          `p_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP  
        ) ENGINE=InnoDB DEFAULT CHARSET=gb2312                   

数据:
insert into t1(p_c) select 4;
update t1 set p_c = 3 where p_c = 3;

1    2007-10-08 11:53:35
2    2007-10-08 12:00:37
3    2007-10-08 12:00:37
4    2007-10-08 12:05:19


3、一个表中不能有两个字段默认值是当前时间,否则就会出错。不过其他的可以。
表:
/*DDL Information For - test.t1*/
---------------------------------

Table   Create Table                                                   
------  ---------------------------------------------------------------
t1      CREATE TABLE `t1` (                                            
          `p_c` int(11) NOT NULL,                                      
          `p_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,       
          `p_timew2` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00'  
        ) ENGINE=InnoDB DEFAULT CHARSET=gb2312                         

数据:
1    2007-10-08 11:53:35    0000-00-00 00:00:00
2    2007-10-08 12:00:37    0000-00-00 00:00:00
3    2007-10-08 12:00:37    0000-00-00 00:00:00
4    2007-10-08 12:05:19    0000-00-00 00:00:00