Listing 1: Inner Procedure usp_lookupPrice
/*1*/ CREATE PROCEDURE usp_lookupPrice
/*2*/    @product_id int,
/*3*/    @product_price money OUTPUT
/*4*/ AS
/*5*/    SELECT @product_price = product_price    
           FROM Products WHERE product_id = @product_id
/*6*/    IF @@rowcount = 0              -- row not found
/*7*/	     RETURN 10
/*8*/    IF @product_price IS NULL  -- unit_price is null
/*9*/  	     RETURN 11
/*10*/   RETURN