防止一年内员工多次涨薪

为以防一年内员工多次涨薪，以下查询代码更保守

select 
    s1.emp_no 
    ,max(s2.from_date)
    ,sum(s2.salary-s1.salary) salary_growth
from salaries s1
inner join salaries s2
on s1.emp_no = s2.emp_no 
    and s1.to_date = s2.from_date
where (s2.salary-s1.salary) > 5000
    and 
    (
        cast(strftime('%Y',s2.to_date) as signed int) 
     - 
        cast(strftime('%Y',s1.from_date) as signed int)
    ) <= 2
group by s1.emp_no
order by salary_growth desc