Hello Rohan Roy,
Step 1. Department and Designation datatype should be set to Text in the entity.
Step 2. Change Dropdown Options value from Department_mst.Id to Department_mst.Deptname.
Same thing for designation.
Thus, you can achieve your task.
As per best practice,
You should save Id's on the table, same as what you are doing currently.
While fetching the result, you can join two entities using these Id's to get the Name.
Kind Regards,
Riyaz