search bar in ASP.NET

Question

hai  friends,

  these are the two textboxes  "EmpId" in Textbox1,and another for  "Employee name. in Textbox2"

so i want to search by "empid", by leaving second textbox as empty 

at the sametime if i left  "first textbox" as empty,and the second textbox with "Employee Name" . 

the data should appaer in the gridview.

 

i had written a query like this ,but iam not getting.

 

SelectCommand="SELECT [id], [EmpId], [FirstName], [MI], [LastName] FROM [Employees] WHERE ((EmpId like '%' +@EmpId + '%' or FirstName like '%' +@FirstName+'%' ))" 

 

pls reply, 

In advance

thanku