替代SQL语句WHERE条件中OR关键词

SQL语句，当WHERE条件需要搜索工号为16或工号为2的雇员姓名时，需用到OR关键词如：

SELECT   [ EmployeeName ]   FROM   [ Employee ]   WHERE   [ WorkNumber ]   =   16   OR   [ WorkNumber ]   =   2

但是，上面SQL语句会涉及效率与性能问题，因为重写上面SQL语句：

 
   
  SELECT 
    
  [ 
  EmployeeName 
  ] 
    
  FROM 
    
  [ 
  Employee 
  ] 
    
  WHERE 
    
  [ 
  WorkNumber 
  ] 
    
  = 
    
  16 
  
 
  UNION 
    
  ALL 
  
 
  SELECT 
    
  [ 
  EmployeeName 
  ] 
    
  FROM 
    
  [ 
  Employee 
  ] 
    
  WHERE 
    
  [ 
  WorkNumber 
  ] 
    
  = 
    
  2