OK you confused me again (not that it's hard to do ) what do you mean by two result sets? I only get one when I run it.
It may not matter. I looked up some of the information_schema views and came up with the following.
select t1.column_name, t1.constraint_name from information_schema.constraint_column_usage t1 inner join information_schema.table_constraints t2 on t1.table_name = t2.table_name and t1.constraint_name = t2.constraint_name where t2.table_name = 'authors' and t2.constraint_type = 'primary key'
This will give you the name of the column and constraint for the primary key of the authors table in the pubs database. Put your table name in it's place and you should be good to go.