mysql view if else problem

I m working with mysql view and i want use IF ELSE statement on that view. its giving me error like this

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'if(getUser()="") THEN]
        select hie_code_1 from hs_hr_emp_level L,hs_hr_u' at line 7 

This is my view

drop view if exists   vw_hs_hr_employee;

CREATE VIEW vw_hs_hr_employee  as 
select * from hs_hr_employee where 
hie_code_1 in 
(
BEGIN

    if(getUser()="") THEN
        select hie_code_1 from hs_hr_emp_level L
    ELSE
           select hie_code_1 from hs_hr_emp_level开发者_如何学编程 L,hs_hr_users U
             where L.emp_number=U.emp_number
               and L.emp_number=getUser()
               and ( U.def_level=1 or U.def_level=4 )
    END if

)  

EDITED here my function

CREATE  FUNCTION `getUser`() RETURNS char(50) CHARSET latin1
RETURN  @user

If any one can help me thanks

UPDATED query

CREATE VIEW vw_hs_hr_employee  as
select * from hs_hr_employee where
CASE getUser()
        WHEN  ''
    THEN 
    select hie_code_1 from hs_hr_emp_level L
    END
hie_code_1 in ( select hie_code_1 from hs_hr_emp_level L,hs_hr_users U   where L.emp_number=U.emp_number and L.emp_number=getUser() and  ( U.def_level=1 or U.def_level=4 )   )
or
 hie_code_3 in ( select hie_code_3 from hs_hr_emp_level L,hs_hr_users U   where L.emp_number=U.emp_number and L.emp_number=getUser() and  U.def_level=2   )
or
  hie_code_4 in ( select hie_code_4 from hs_hr_emp_level L,hs_hr_users U   where L.emp_number=U.emp_number and L.emp_number=getUser() and  U.def_level=3 ) 

givinign error syntax to use near 'select hie_code_1 from hs_hr_emp_level L END hie_code_1 in ( select hie_code_' at line 6

Done

drop view if exists  vw_hs_hr_employee;
CREATE VIEW vw_hs_hr_employee  as
select * from hs_hr_employee e where CASE WHEN getUser()=''
    THEN
     e.emp_number is not null
    ELSE
hie_code_1 in ( select hie_code_1 from hs_hr_emp_level L,hs_hr_users U   where L.emp_number=U.emp_number and L.emp_number=getUser() and  ( U.def_level=1 or U.def_level=4 )   )
or
 hie_code_3 in ( select hie_code_3 from hs_hr_emp_level L,hs_hr_users U   where L.emp_number=U.emp_number and L.emp_number=getUser() and  U.def_level=2   )
or
  hie_code_4 in ( select hie_code_4 from hs_hr_emp_level L,hs_hr_users U   where L.emp_number=U.emp_number and L.emp_number=getUser() and  U.def_level=3 )

end

As Conspicuous commented, a View can hold a simple SELECT statement.

You can use a single query with CASE block:

CREATE VIEW vw_hs_hr_employee  as 
SELECT *
FROM hs_hr_employee
WHERE CASE WHEN getUser() = ''
    THEN hie_code_1 IN (
        SELECT hie_code_1
        FROM hs_hr_emp_level)
    ELSE hie_code_1 IN (
        SELECT hie_code_1
        FROM hs_hr_emp_level L,hs_hr_users U
             WHERE L.emp_number=U.emp_number
               AND L.emp_number=getUser()
               AND ( U.def_level=1 or U.def_level=4))
    END

Or use a join based query, (creating a 2nd view to workaround the MySql limitation):

DROP VIEW IF EXISTS vw_hs_hr_employee_sub;

CREATE VIEW vw_hs_hr_employee_sub AS
SELECT hie_code_1
FROM hs_hr_emp_level L
    LEFT JOIN hs_hr_users U
        ON L.emp_number = U.emp_number
        AND L.emp_number = getUser()
        AND ( U.def_level=1 or U.def_level=4 )
WHERE getUser() = '' OR U.emp_number IS NOT NULL
GROUP BY 1;


drop view if exists   vw_hs_hr_employee;

CREATE VIEW vw_hs_hr_employee  as 
SELECT e.*
FROM hs_hr_employee e JOIN vw_hs_hr_employee_sub USING(hie_code_1)

Use single quotes!

...
if(getUser()='') THEN
...