How to replace comma separated department ids with their name respectively?

Question

My tables are these :

Employee Table:

+-----------+----------+------------+
| id       | name     | department  |
+-----------+----------+-----------         


        

Answer 1

SELECT replace(replace(department,'1','CS'),'2','IT')  as dept  from Employee

Answer 2

You should avoid storing data as comma-separated values, and follow normalization.

However in this case you can do something as

select 
e.id , 
e.name , 
group_concat(d.name) from employee e 
left join department d on find_in_set(d.id,e.department) 
group by e.id ;