private void btnGetSalary_Click(object sender, EventArgs e)
        {
            SqlParameter parameterId     = new SqlParameter("@Id", SqlDbType.Int);
            SqlParameter parameterSalary = new SqlParameter("@Salary", SqlDbType.Money);

            parameterSalary.Direction = ParameterDirection.Output;
            parameterId.Value         = txtId.Text;

            DatabaseUtility.ExecuteStoredProcedureNonQuery("GetSalary", parameterId, parameterSalary);

            if (parameterSalary.Value == DBNull.Value)
            {
                MessageBox.Show("0");
            }
            else
            {
                MessageBox.Show(parameterSalary.Value.ToString());
            }
        }