Is there a SELECT statement to subtract rows of the same column? Column 1 is the mem_id, Column 2 is the Transaction type C and D, and Column 3 is the Amount Owed. So I want to return Column 3 "Amount Owed", but it has to be C-D in Column 2 for each member. thanks, I hope that helps.
If I understood your question correctly...

SELECT mem_id, 
       Sum(CASE TranType 
             WHEN 'C' THEN Amount 
             WHEN 'D' THEN -Amount 
           END) AS Amount_Owed 
FROM   YourTable 
GROUP  BY mem_id;