Implementing DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT

With the DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP, a column has the current timestamp for its default value and is automatically updated to the current timestamp.

Let us see an example and create a table −

mysql> create table DemoTable737 (
   StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   StudentName varchar(100),
   StudentAdmissiondate datetime
);
Query OK, 0 rows affected (0.68 sec)

Following is the query to for CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP in MySQL −

mysql> alter table DemoTable737 modify column StudentAdmissiondate 
timestamp DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP;
Query OK, 0 rows affected (2.20 sec)
Records: 0 Duplicates: 0 Warnings: 0

Let us check the description of table once again −

mysql> desc DemoTable737;

This will produce the following output -

+----------------------+--------------+------+-----+-------------------+-----------------------------+
| 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)

Implementing DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP in MySQL