在MySQL中实现DEFAULT CURRENT_TIMESTAMP和ON UPDATE CURRENT_TIMESTAMP
使用DEFAULTCURRENT_TIMESTAMP和ONUPDATECURRENT_TIMESTAMP时，列具有默认值的当前时间戳，并自动更新为当前时间戳。
让我们看一个例子并创建一个表-
mysql> create table DemoTable737 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(100), StudentAdmissiondate datetime );
以下是对MySQL中的CURRENT_TIMESTAMP和ONUPDATECURRENT_TIMESTAMP的查询-
mysql> alter table DemoTable737 modify column StudentAdmissiondate timestamp DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP; Records: 0 Duplicates: 0 Warnings: 0
让我们再次检查表的描述-
mysql> desc DemoTable737;
这将产生以下输出-
+----------------------+--------------+------+-----+-------------------+-----------------------------+ | Field | Type | Null | Key | Default | Extra | +----------------------+--------------+------+-----+-------------------+-----------------------------+ | StudentId | int(11) | NO | PRI | NULL | auto_increment | | StudentName | varchar(100) | YES | | NULL | | | StudentAdmissiondate | timestamp | YES | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP | +----------------------+--------------+------+-----+-------------------+-----------------------------+ 3 rows in set (0.01 sec)