private void b_Add_Click(object sender, EventArgs e)
        {
            if (tid.Text == string.Empty || tname.Text == string.Empty || tpay.Text == string.Empty || tsalary.Text == string.Empty)
            {
                MessageBox.Show("Please Fillup all the text fields!!");
            }
            else
            {
                if (Double.Parse(tpay.Text) <= Double.Parse(tsalary.Text))
                {
                    double x = Double.Parse(tsalary.Text) - Double.Parse(tpay.Text);
                    lAmount.Text = x.ToString();



                    SalaryService sal    = new SalaryService();
                    int           result = sal.Insert(new Salary()
                    {
                        Eid           = Convert.ToInt16(tid.Text),
                        Name          = tname.Text,
                        Month         = dateTimePicker1.Value.Month.ToString(),
                        Pay           = Double.Parse(tpay.Text),
                        Total_Salary  = Double.Parse(tsalary.Text),
                        Remain_salary = x,
                        Year          = tyear.Value.Year.ToString()
                    });
                    if (result > 0)
                    {
                        MessageBox.Show("Salary added.");
                    }
                    else
                    {
                        MessageBox.Show("Error");
                    }
                }
                else
                {
                    MessageBox.Show("Payment is greater than total salary ");
                }
            }
        }