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,depart ment 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