Creating a column interger with default to not null

[Chris Barnes <compuguruchrisbarnes@xxxxxxxxxxx>]

I am confused with what this is telling me.
I have a table and I am trying to add a new column with constraint not null.


What am I missing?
Chris


pgdb001=> alter table schema.table add COLUMN column_name integer not null;
ERROR:  column "column_name" contains null values