sqlsql-serverdefault-valuealter-tablealter-column

Change a Nullable column to NOT NULL with Default Value


I came across an old table today with a datetime column called 'Created' which allows nulls. Now, I'd want to change this so that it is NOT NULL, and also include a constraint to add in a default value (getdate()).

So far I've got the following script, which works fine provided that I've cleaned up all the nulls beforehand:

ALTER TABLE dbo.MyTable ALTER COLUMN Created DATETIME NOT NULL 

Is there any way to also specify the default value as well on the ALTER statement?


Solution

  • I think you will need to do this as three separate statements. I've been looking around and everything I've seen seems to suggest you can do it if you are adding a column, but not if you are altering one.

    ALTER TABLE dbo.MyTable
    ADD CONSTRAINT my_Con DEFAULT GETDATE() for created
    
    UPDATE MyTable SET Created = GetDate() where Created IS NULL
    
    ALTER TABLE dbo.MyTable 
    ALTER COLUMN Created DATETIME NOT NULL