C#のDataBaseの操作について

	public class ConnectionDatabase2
	{

		static OleDbConnection cn;
		static OleDbDataAdapter da;
		static DataTable tbl;

		public ConnectionDatabase2()
		{
			// 
			// TODO: コンストラクタ ロジックをここに追加してください。
			//
			
		}

		/// <summary>
		///  メインメソッド
		/// </summary>
		public void MianMethod()
		{
			string strConn ,strSql;
			strConn = "user id=user;"
				+ "password=pass;"
				+ "initial catalog=hogeDB;"
				+ "data source=192.168.1.3;"
				+ "Provider=SQLOLEDB;"
				+ "Trusted_Connection=Yes;"
				;
			strSql = "SELECT OrderID,ProductID,Quantity,UnitPrice FROM OrderDetails WHERE OrderID = 10503 ORDER BY ProductID" ;

			cn = new OleDbConnection(strConn);
			da = new OleDbDataAdapter(strSql,cn);
			tbl = GenTable();

			cn.Open();
			ResetOrder();

		}

		#region "初期化処理"
		/// <summary>
		/// 初期化処理
		/// </summary>
		static void ResetOrder()
		{
			OleDbCommand cmd = cn.CreateCommand();
			cmd.CommandText = "DELETE FROM OrderDetails WHERE OrderID = 10503";
			cmd.ExecuteNonQuery();

			cmd.CommandText = "INSERT INTO OrderDetails(OrderID,ProductID,Quantity,UnitPrice) VALUES (10503,14,70,23.25)";
			cmd.ExecuteNonQuery();

			cmd.CommandText = "INSERT INTO OrderDetails(OrderID,ProductID,Quantity,UnitPrice) VALUES (10503,65,20,21.05)";
			cmd.ExecuteNonQuery();
		}
		#endregion

		#region "Define"
		/// <summary>
		/// テーブル定義
		/// </summary>
		/// <returns></returns>
		static DataTable GenTable()
		{
			DataTable tbl = new DataTable("Order Details");
			DataColumn col;

			col = tbl.Columns.Add("OrderID",typeof(int));
			col.AllowDBNull = false;

			col = tbl.Columns.Add("ProductID",typeof(int));
			col.AllowDBNull = false;

			col = tbl.Columns.Add("Quantity",typeof(Int16));
			col.AllowDBNull = false;

			col = tbl.Columns.Add("UnitPrice",typeof(Decimal));
			col.AllowDBNull = false;

			tbl.PrimaryKey = new DataColumn[] {tbl.Columns["OrderID"],tbl.Columns["ProductID"]};

			return tbl;
		}
		#endregion

	}

	OleDbCommand cmd = cn.CreateCommand();
	cmd.CommandText = "DELETE FROM OrderDetails WHERE OrderID = 10503";
	cmd.ExecuteNonQuery();