C# WinApp เอา clsDatabase มาฝากครับเผื่อมีท่านใดอยากต่อยอด

using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace TORServices
{
   public static class clsDatabase
   {
       public enum EnumConnectionType { ODBC, OLEDB, SqlClient }
       public static string connectionString="";
       public static System.Data.DataTable GetTableForm(string _SQL,  EnumConnectionType ConnectionType)
       {
           System.Data.DataSet ds = new System.Data.DataSet();
           switch (ConnectionType)
           {
               case EnumConnectionType.ODBC:
                   System.Data.Odbc.OdbcConnection conn1 = new System.Data.Odbc.OdbcConnection(connectionString);
                   conn1.Open();
                   System.Data.Odbc.OdbcDataAdapter adapter1 = new System.Data.Odbc.OdbcDataAdapter(_SQL, conn1);
                   adapter1.Fill(ds);
                   break;
               case EnumConnectionType.OLEDB:
                   System.Data.OleDb.OleDbConnection conn2 = new System.Data.OleDb.OleDbConnection(connectionString);
                   conn2.Open();
                   System.Data.OleDb.OleDbDataAdapter adapter2 = new System.Data.OleDb.OleDbDataAdapter(_SQL, conn2);
                   adapter2.Fill(ds);
                   break;
               case EnumConnectionType.SqlClient:
                   System.Data.SqlClient.SqlConnection conn3 = new System.Data.SqlClient.SqlConnection(connectionString);
                   conn3.Open();
                   System.Data.SqlClient.SqlDataAdapter adapter3 = new System.Data.SqlClient.SqlDataAdapter(_SQL, conn3);
                   adapter3.Fill(ds);

                   break;
           }

           return ds.Tables[0];

       }
       public static System.Windows.Forms.ComboBox DatabaseInCombobox(string _SQL, string strConn, EnumConnectionType ConnectionType)
       {
           ComboBox cmb = new ComboBox();
           cmb.DataSource = GetTableForm(_SQL,  ConnectionType);
           return cmb;
       }
       public static string[] GetData(string field, string table, string strConn, EnumConnectionType ConnectionType)
       {
           DataTable dt = GetTableForm("Select " + field + " FROM " + table,  ConnectionType);
           string[] str = new string[dt.Rows.Count];
           for (int i = 0; i < dt.Rows.Count; i++)
           {
               str[i] = dt.Rows[i][field].ToString();
           }
           return str;

       }
       public static DataRow GetDataRow(string sql, string strConn, EnumConnectionType ConnectionType)
       {
           DataTable dt = GetTableForm(sql,  ConnectionType);

           return dt.Rows[0];

       }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            TORServices.clsDatabase.connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=X:\\DATA\\PostCode.mdb;Jet OLEDB:Database Password=4410210091";
            comboBox1.DataSource = TORServices.clsDatabase.GetTableForm("SELECT Amphur FROM Sett_Post_Amphur", TORServices.clsDatabase.EnumConnectionType.OLEDB);
            comboBox1.DisplayMember = "Amphur";
            dataGridView1.DataSource = TORServices.clsDatabase.GetTableForm("SELECT *  FROM Sett_Post_PostCode", TORServices.clsDatabase.EnumConnectionType.OLEDB);

        }
    }
}