[sql-server] insert a NOT NULL column to an existing table

I have tried:

ALTER TABLE MY_TABLE 
ADD STAGE INT NOT NULL;

But it gives this error message:

ALTER TABLE only allows columns to be added that can contain nulls or have a DEFAULT definition specified

This question is related to sql-server alter-table notnull

The answer is


Alter TABLE 'TARGET' add 'ShouldAddColumn' Integer Not Null default "0"

The error message is quite descriptive, try:

ALTER TABLE MyTable ADD Stage INT NOT NULL DEFAULT '-';

This worked for me, can also be "borrowed" from the design view, make changes -> right click -> generate change script.

BEGIN TRANSACTION
GO
ALTER TABLE dbo.YOURTABLE ADD
    YOURCOLUMN bit NOT NULL CONSTRAINT DF_YOURTABLE_YOURCOLUMN DEFAULT 0
GO
COMMIT

If you aren't allowing the column to be Null you need to provide a default to populate existing rows. e.g.

ALTER TABLE dbo.YourTbl ADD
    newcol int NOT NULL CONSTRAINT DF_YourTbl_newcol DEFAULT 0

On Enterprise Edition this is a metadata only change since 2012


ALTER TABLE `MY_TABLE` ADD COLUMN `STAGE` INTEGER UNSIGNED NOT NULL AFTER `PREV_COLUMN`;

Other SQL implementations have similar restrictions. The reason is that adding a column requires adding values for that column (logically, even if not physically), which default to NULL. If you don't allow NULL, and don't have a default, what is the value going to be?

Since SQL Server supports ADD CONSTRAINT, I'd recommend Pavel's approach of creating a nullable column, and then adding a NOT NULL constraint after you've filled it with non-NULL values.