There may be better ways to achieve what you need, such as by using an identity column or perhaps calculating the column in a view or in the queries against the table.However, if you did want to do this, one way to it would be using a UDF as follows:Define a UDF:create FUNCTION dbo.fn_Table1Col1MaxValue() returns intasbegin return (select isnull(max(col1+1),1) as maxVal from Table1);endGO
Then, use the UDF to define the constraint:create table Table1 ( col1 int default dbo.fn_Table1Col1MaxValue(), col2 varchar(10))
The usual restrictions about UDF's will apply, and it is schema-bound, so if you need to alter it you will need to drop the constraint first etc.