Trying to update a column with a unique value

[freyc]

I am going to be updating columns 1 and column 2 with common values. The third column I want to assign a number value. Starting at 1 and stopping when there are no more that meet the particular values set in columns 1 or 2 and that column 3 is no longer NULL.

I do not care if this is done via a trigger, stored procedure, or simply a SQL statement.

Please help me out.