A DEFAULT value is a constraint. Constraints can be placed in one of two ways: on a column, or on a table.
A column DEFAULT can only be added when you create the table or when you add a column to a table.
But, you can define a table constraint which is a DEFAULT constraint FOR a given column:
Code:
ALTER TABLE yourtable
ADD CONSTRAINT someconstraintname DEFAULT <yourdefaultvalue>
FOR yourcolumn;
By convention DEFAULT constraints are given a name beginning with DF_ if you add then via EM, but you can call it anything you like as long as it is a unique constraint name.
It's sometimes handy to make the change in EM in table design mode, then click the generate script toolbar button and look at what EM would to to effect the change you want to make to the table. What it chooses to do may not always be the most efficient way to do it, but the way it chooses has the advantage that it always (almost, anyway ;)) works.
Jeff Mason
Custom Apps, Inc.
www.custom-apps.com
ALTER TABLE syntax
