Returning result sets from procedures

Result sets allow a procedure to return more than one row of results to the calling environment.

The following procedure returns a list of customers who have placed orders, together with the total value of the orders placed. The procedure does not list customers who have not placed orders.

CREATE PROCEDURE ListCustomerValue ()
RESULT ("Company" CHAR(36), "Value" NUMERIC(14,2))
BEGIN
	SELECT company_name, 
		CAST( sum(	sales_order_items.quantity * 
						product.unit_price)
						AS NUMERIC(14,2)) AS value
	FROM customer
		INNER JOIN sales_order 
		INNER JOIN sales_order_items 
		INNER JOIN product 
	GROUP BY company_name 
	ORDER BY value DESC;
END

• Type the following:

CALL ListCustomerValue ()

• The number of variables in the RESULT list must match the number of the SELECT list items. Automatic data type conversion is carried out where possible if data types do not match.

• The RESULT clause is part of the CREATE PROCEDURE statement, and does not have a command delimiter.

• The names of the SELECT list items do not need to match those of the RESULT list.

• When testing this procedure, dbisql displays only the first result set by default. You can configure dbisql to display more than one result set by setting the Show multiple result sets option on the Commands tab of the Options dialog.

• You can modify procedure result sets, unless they are generated from a view. The user calling the procedure requires the appropriate permissions on the underlying table to modify procedure results. This is different than the usual permissions for procedure execution, where the procedure owner must have permissions on the table.