How do I remove ON UPDATE CURRENT_TIMESTAMP from an existing column in MySQL?

MySQLMySQLi Database

The ON UPDATE CURRENT_TIMESTAMP defines that an update without an explicit timestamp would result in an update to the current timestamp value.

You can remove ON UPDATE CURRENT_TIMESTAMP from a column using ALTER command.

The syntax is as follows

ALTER TABLE yourTableName
CHANGE yourTimeStampColumnName yourTimeStampColumnName timestamp NOT
NULL default CURRENT_TIMESTAMP;

To understand the above syntax, let us create a table. The query to create a table is as follows

mysql> create table removeOnUpdateCurrentTimeStampDemo
   - > (
   - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   - > Name varchar(20),
   - > UserUpdateTimestamp timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP
   - > );
Query OK, 0 rows affected (0.54 sec)

Check the description of the table using DESC command.

The query is as follows

mysql> desc removeOnUpdateCurrentTimeStampDemo;

The following is the output

+---------------------+-------------+------+-----+-------------------+-----------------------------+
| Field               | Type        | Null | Key | Default           | Extra                       |
+---------------------+-------------+------+-----+-------------------+-----------------------------+
| Id                  | int(11)     | NO   | PRI | NULL              | auto_increment              |
| Name                | varchar(20) | YES  |     | NULL              |                             |
| UserUpdateTimestamp | timestamp   | NO   |     | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+---------------------+-------------+------+-----+-------------------+-----------------------------+
3 rows in set (0.04 sec)

Now look at the Extra field there is on update CURRENT_TIMESTAMP. The query to remove ON UPDATE CURRENT_TIMESTAMP is as follows:

mysql> alter table removeOnUpdateCurrentTimeStampDemo
   - > change UserUpdateTimestamp UserUpdateTimestamp timestamp NOT NULL default CURRENT_TIMESTAMP;
Query OK, 0 rows affected (0.16 sec)
Records: 0 Duplicates: 0 Warnings: 0

Check the description of table once again.

The query is as follows

mysql> desc removeOnUpdateCurrentTimeStampDemo;

The following is the output

+---------------------+-------------+------+-----+-------------------+----------------+
| Field               | Type        | Null | Key | Default           | Extra          |
+---------------------+-------------+------+-----+-------------------+----------------+
| Id                  | int(11)     | NO   | PRI | NULL              | auto_increment |
| Name                | varchar(20) | YES  |     | NULL              |                |
| UserUpdateTimestamp | timestamp   | NO   |     | CURRENT_TIMESTAMP |                |
+---------------------+-------------+------+-----+-------------------+----------------+
3 rows in set (0.00 sec)

If you want to remove the default CURRENT_TIMESTAMP, then the query is as follows

mysql> alter table removeOnUpdateCurrentTimeStampDemo
   - > change UserUpdateTimestamp UserUpdateTimestamp timestamp NOT NULL;
Query OK, 0 rows affected (0.12 sec)
Records: 0 Duplicates: 0 Warnings: 0

Check the description of table once again.

The query is as follows

mysql> desc removeOnUpdateCurrentTimeStampDemo;

The following is the output

+---------------------+-------------+------+-----+---------+----------------+
| Field               | Type        | Null | Key | Default | Extra          |
+---------------------+-------------+------+-----+---------+----------------+
| Id                  | int(11)     | NO   | PRI | NULL    | auto_increment |
| Name                | varchar(20) | YES  |     | NULL    |                |
| UserUpdateTimestamp | timestamp   | NO   |     | NULL    |                |
+---------------------+-------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)

Now look at the above sample output, we have removed the ON UPDATE CURRENT TIMESTAMP.

raja
Published on 19-Mar-2019 15:18:57
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