Find lowest mark from student table to label using c#

Create Proc TestQry
as
Select TOP(1) Salary,Department from employee group BY Department,salary order BY Salary

protected void bt1_Click(object sender, EventArgs e)
    {
        try
        {
        con.Open();
        SqlCommand sqlcmd = new SqlCommand("TestQry", con);
         lblMin.Text = " Min Salary : " +  Convert.ToDecimal(sqlcmd.ExecuteScalar()).ToString();
        }
        catch (Exception ex)
        {

        }

    }