How To Test A Lamda Expression Variabe Query Result Is Null?.

var query = from emp in dbEmp.Employees join dept in dbEmp.Departments on emp.DeptID equals dept.DeptID where dept.DepartmentName.Contains(this.TextBox1.Text) select new { EmpID = emp.EmpID, EmpName = emp.EmpName, Age = emp.Age, Address = emp.Address, DeptName
= dept.DepartmentName };

if (query==null) Label1.Text = "no results match your search";

GridView1.DataSource = query; GridView1.DataBind();

Everything works in the right way, but the label doesn't show the message when query result returns null. The label can show without condition(querry==null). So how to test if a var query result returns nothing?