Alter Table - MySQL Command

Drop Column:

alter table icecream drop column flavor ;

Drop Column is used to remove an entire column and all its data from a table.

Add Column:

alter table icecream add column flavor varchar (20) ;

Add Column is used to add a column to your existing table.

Change:

alter table icecream change taste flavor varchar (10) ;

Change is used to change the column name. In our example it changes "taste" to be "flavor".

Add Unique:

alter table icecream add unique (quantity)

Add unique adds a new column to your table only if it does not already exist.

Modify:

alter table icecream modify flavor VARCHAR(35) ;

Modify is used to change a column's size. In our example we increase the size of the "flavor" column to 35 characters.