If you have an existing column in a table and you want to change the column name, you can use the "ALTER TABLE ... CHANGE" statement. This statement allows you to change the name of a column, and its definition. The tutorial script below gives you a good example:
mysql> ALTER TABLE test CHANGE COLUMN subject
title VARCHAR(60);
Query OK, 1 row affected (0.51 sec)
Records: 1 Duplicates: 0 Warnings: 0