How to make search based on categories

[msdhh]

Hi there,
I'm new to programming and I started learning C# three months ago so I need your help please.

I have three tables (company,department and employee).
Company table has two rows (CompanyID, CompanyName). Department table has four rows (DeptID, DeptName, CompanyID, EmpID).
Employee table has three rows (EmpID, EmpName, EmpAddress).

I want to search by Departments
For example I want to have one Checkbox named Department if I checked Department it should show me all the available departments in the Company so if i select a particular department it should show me all the employees that they belong to the department that has been selected. I kindly request to shed a light on this topic in details.
your help is greatly appreciated

[PreethiGowri]

you can use table joins

[msdhh]

thank you I will try that

[rubenrp81]

employee, must be a department colummn too. and then make select based in that