Suppose there is an employee table with columns EmployeeID, Name, Gender etc and there is a Leaves table with Totalleaves, RemainingLeaves and Status where status is either 0 or 1 and denotes if the employee has taken leave or not for a particular day (0- no leave, 1-leave taken)

Suppose there is an employee table with columns EmployeeID, Name, Gender etc and there is a Leaves table with Totalleaves, RemainingLeaves and Status where status is either 0 or 1 and denotes if the employee has taken leave or not for a particular day (0- no leave, 1-leave taken). 

How can we check and update if an employee is eligible to take leaves based on RemainingLeaves in a Leave table where RemainingLeaves should be more than 5? 

Should we use a trigger or stored function because we want to update the eligibility is a column too so we can check later on?

Use MYSQL, please elaborate as well.