how to show more than one foreign key values rather than their id's in

One of my table (user) contains 2 foreign keys named as (designation_id from designation table) and (department_id from department table),while view my (table user),the foreign key id's show.I want these foreign keys value rather than id while viewing the (table user).I wrote this query but it does not work and this query works only when i just want the only one foreign key value either it is (designation_id from designation table) or (department_id from department table) but not work on both.So what did i do?
SELECT user_id,user_name,address,phone_no,designation.designation_id,grade,registration,department.dept_id ,designation.designation,department.department
FROM user
LEFT JOIN designation and department
ON user.designation_id = designation.designation_id,
ON user.dept_id = department.dept_id;