An ADO.NET multi-database, multi-tier solution

using System;
using System.Data;
using System.Data.OleDb;
using System.Globalization;

namespace MultiTier.Data {

	public abstract class OleDB : Data {

		#region Enumerators

		#endregion

		#region Constructors
		
		protected OleDB(string connection) : base(connection) {
		}
		
		#endregion

		#region Variables
		
		// Connection
		private OleDbConnection cnConnection;

		// DataAdapter
		private OleDbDataAdapter daDataAdapter;

		#endregion

		#region Properties

		public OleDbConnection Connection {
			get { return cnConnection; }
			set { cnConnection = value; }
		}

		public OleDbDataAdapter DataAdapter {
			get { return daDataAdapter; }
			set { daDataAdapter = value; }
		}

		#endregion

		#region Methods

		protected abstract override void ConstructDataAdapter();

		public override DataTable ReadData() {
			//--- Create a new DataSet
			this.Table = new DataTable(this.TableName);
			this.Table.Locale = CultureInfo.InvariantCulture;

			try {
				//--- Fill the DataSet with the Customers
				daDataAdapter.Fill(this.Table);
				//--- Return the DataSet
				return this.Table;
			}
			catch (OleDbException ex) {
				//--- An error occurred, so we roll the transaction back
				this.CurrentException = ex;
				//--- Return the DataSet
				return this.Table;
			}
		}

		public override void SaveData(DataTable dataTable) {
			this.Table = dataTable;
			OleDbTransaction trTransaction = null;

			//---------------------------------------------------------
			//--- Save the data
			//---------------------------------------------------------
			try {
				//--- Set up the conection manually
				InitializeConnection();
				cnConnection.Open();
				//--- Begin a transaction 
				trTransaction = cnConnection.BeginTransaction();
				//--- Make all database changes
				this.AffectedRecords = daDataAdapter.Update(this.Table);
				//--- Commit the changes
				trTransaction.Commit();
			}
			catch (DBConcurrencyException ex) {
				//--- An error occurred, so we roll the transaction back
				this.CurrentException = ex;
				trTransaction.Rollback();
			}
			catch (OleDbException ex) {
				//--- An error occurred, so we roll the transaction back
				this.CurrentException = ex;
				trTransaction.Rollback();
			}
			finally {
				//--- Close the connection that we manually opened
				trTransaction = null;
				cnConnection.Close();
				cnConnection = null;
			}
		}


		public override void InitializeConnection() {
			cnConnection = new OleDbConnection(this.ConnectionString);
		}
 

		#endregion
	}
}