Is there a way to convert Integer field into Varchar without losing data in MySQL?

You can use ALTER command to convert Integer into Varchar. Let us first create a table

mysql> create table DemoTable (    UserId int,    UserFirstName varchar(20),    UserLastName varchar(20),    UserAge int ); Query OK, 0 rows affected (0.73 sec)

Now 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)     | YES | | NULL | | | UserFirstName | varchar(20) | YES | | NULL | | | UserLastName  | varchar(20) | YES | | NULL | | | UserAge       | int(11)     | YES | | NULL | | +---------------+-------------+------+-----+---------+-------+ 4 rows in set (0.17 sec)

Now you can change the integer data type to varchar without losing data:

mysql> alter table DemoTable change UserId UserId varchar(20); Query OK, 0 rows affected (1.35 sec) Records: 0 Duplicates: 0 Warnings: 0

Check the table description:

mysql> desc DemoTable;

This will produce the following output −

+---------------+-------------+------+-----+---------+-------+ | Field         | Type        | Null | Key | Default | Extra | +---------------+-------------+------+-----+---------+-------+ | UserId        | varchar(20) | YES  |     | NULL   | | | UserFirstName | varchar(20) | YES | | NULL | | | UserLastName | varchar(20) | YES | | NULL | | | UserAge | int(11) | YES | | NULL | | +---------------+-------------+------+-----+---------+-------+ 4 rows in set (0.00 sec)