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How to change MySQL column definition?
To change MySQL column definition, we can use modify or change clause with ALTER command. Let us first create a table with a column as ID, with int data type. We will modify the same column name with varchar data type.
Creating a table.
mysql> create table ModifyColumnDemo -> ( -> id int -> ); Query OK, 0 rows affected (0.52 sec)
Now, let us write the syntax to change the column definition. The syntax is as follows −
alter table yourTableName modify column columnName data type;
Apply the above syntax to change the MySQL definition.
mysql> alter table ModifyColumnDemo modify column id varchar(10) not null; Query OK, 0 rows affected (1.52 sec) Records: 0 Duplicates: 0 Warnings: 0
Let us now check whether the column has been change with the new data type or not. For that, we will be using the DESC command.
mysql> desc ModifyColumnDemo;
The following is the output.
+-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | id | varchar(10) | NO | | NULL | | +-------+-------------+------+-----+---------+-------+ 1 row in set (0.15 sec)
You can see in the above output, we have changed the column definition with new datatype varchar.
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