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How to update a column of varchar type in MySQL to increase its length?
Let us first create a table. Here, we have two columns with varchar type −
mysql> create table DemoTable ( UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, UserFirstName varchar(10), UserLastName varchar(20) , UserAge int ); Query OK, 0 rows affected (0.96 sec)
Let us check the description of table using DESC command −
mysql> desc DemoTable;
This will produce the following output −
+---------------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+-------------+------+-----+---------+----------------+ | UserId | int(11) | NO | PRI | NULL | auto_increment | | UserFirstName | varchar(10) | YES | | NULL | | | UserLastName | varchar(20) | YES | | NULL | | | UserAge | int(11) | YES | | NULL | | +---------------+-------------+------+-----+---------+----------------+ 4 rows in set (0.00 sec)
Following is the query to update a column of varchar type in MySQL to increase its length −
mysql> alter table DemoTable modify UserFirstName varchar(40); Query OK, 0 rows affected (0.23 sec) Records: 0 Duplicates: 0 Warnings: 0
Let us check the description of table once again to check what we did above. We updated the length of varchar type −
mysql> desc DemoTable;
This will produce the following output −
+---------------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+-------------+------+-----+---------+----------------+ | UserId | int(11) | NO | PRI | NULL | auto_increment | | UserFirstName | varchar(40) | YES | | NULL | | | UserLastName | varchar(20) | YES | | NULL | | | UserAge | int(11) | YES | | NULL | | +---------------+-------------+------+-----+---------+----------------+ 4 rows in set (0.00 sec)
Updated on: 30-Jul-2019
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