How do you create a new varible?

[fert]

How do you create a new varible in an existing row?

[effigy]

I don't understand. Do you mean a @variable? or perhaps a field? (alter table...)

[fert]

[quote author=effigy link=topic=111616.msg452609#msg452609 date=1161008578]
a field? (alter table...)
[/quote]
I mean a field

[a2bardeals]

ALTER TABLE `YOUR_TABLE_NAME` ADD `YOUR_FIELD_NAME` YOUR_FEILD_TYPE NOT NULL ;

a field type is like text (TEXT) or integer (INT).

more field types
http://dev.mysql.com/doc/refman/4.1/en/data-types.html

if you want just a normal string variable like a 'username' and your table is named 'table1' your query might look like:

ALTER TABLE `table1` ADD `username` TEXT NOT NULL