The product between any consecutive integers in MSSQL

The product between any consecutive integers.

Code

  --  Modify exce p_test ?,? Numeric value change  
--  Author: [DBA] Xiaoqi  
  
  If     Exists  (  Select  Name  From Sysobjects  Where  Name  =  '  P_test  '     And  Type  =  '  P  '  )
  Drop     Procedure P_test
  Go  
  Create     Proc  P_test
  @ Start_num     Int  ,
  @ End_num     Int  
  As  
  Declare    @ Cyc     Int  
  Declare     @ Size     Int  
  Declare     @ Count     Int  
  Begin 
  Set     @ Cyc  =  1  
  Set     @ Size  =  (  @ End_num  -  @ Start_num  )
  Set    @ Count  =  @ Start_num  
  While     @ Cyc  <=  @ Size   
  Begin  
  Set     @ Start_num  =  @ Start_num  + 1  
  Set     @ Count  =  @ Count  *  @ Start_num  
  Set     @ Cyc  =  @ Cyc  +  1  
 End  
  Select     @ Count  
  End  
  Go  
  Exec  P_test  1  ,  5