SELECT 
    EMP_CODE, 
    EMP_NAME, 
    SEX, 
    BIRTHDAY
FROM 
    TBL_EMPLOYEES
WHERE 
    (EMP_CODE <= 4 
    AND BIRTHDAY >= '1981-01-01'
    AND BIRTHDAY <= '1981-12-31')
    OR
    (SEX = 'M' 
    AND BIRTHDAY >= '1981-01-01'
    AND BIRTHDAY <= '1981-12-31')
ORDER BY EMP_CODE
;