By using ALTER command we can add columns to an existing table.
Syntax
Alter table table-name ADD (column-name datatype);
Example
In the example below, with the help of ALTER Command, column ‘GRADE’ is added to the table ‘Student’.
mysql> Alter table Student ADD (Grade Varchar(10)); Query OK, 5 rows affected (1.05 sec) Records: 5 Duplicates: 0 Warnings: 0