C# form problem

I have problem in C# form connection with SQL Server I have two tables in SQL Server as Employee Informatioin and Salary Advance

Employee Information Fields as follows

EmpIDEmpNameEmpDesignation (EmpID is Primary Key here)

Salary Advance Fields as follows

EmpIDAdvanceDeduction (EmpID is Foriegn Key here)

what I want in C# form1, if EmpID from Employee Information matches Salary Advance table EmpID then Deduction field from Salary advance should be shown in text box else it should show zero.