G. Use EXECUTE with DEFAULT
This example creates a stored procedure with default values for the first and third parameters. When the procedure is run, these defaults are inserted for the first and third parameters if no value is passed in the call or if the default is specified. Note the various ways the DEFAULT keyword can be used. 

USE pubs
IF EXISTS (SELECT name FROM sysobjects 
      WHERE name = 'proc_calculate_taxes' AND type = 'P')
   DROP PROCEDURE proc_calculate_taxes
GO
 -- Create the stored procedure.
 
CREATE PROCEDURE proc_calculate_taxes (@p1 smallint =  42 , @p2 char( 1 ), 
      @p3 varchar( 8 ) = 'CAR')
    AS 
   SELECT * 
   FROM mytable

The proc_calculate_taxes stored procedure can be executed in many combinations: 

EXECUTE proc_calculate_taxes @p2 = 'A'
EXECUTE proc_calculate_taxes  69 , 'B'
EXECUTE proc_calculate_taxes  69 , 'C', 'House'
EXECUTE proc_calculate_taxes @p1 = DEFAULT, @p2 = 'D'
EXECUTE proc_calculate_taxes DEFAULT, @p3 = 'Local', @p2 = 'E'
EXECUTE proc_calculate_taxes  69 , 'F', @p3 = DEFAULT
EXECUTE proc_calculate_taxes  95 , 'G', DEFAULT
EXECUTE proc_calculate_taxes DEFAULT, 'H', DEFAULT
EXECUTE proc_calculate_taxes DEFAULT, 'I', @p3 = DEFAULT