Want your feedback on my first object in C# (with sample solution now!)

[dee-u]

Complicated it even further...

Base class:

using System;
using System.Configuration;
using System.Data;
using System.Data.Common;
using System.Data.SqlClient;
using System.Data.OleDb;
using System.Windows.Forms;
using DataAccess;

public abstract class BaseClass : IDisposable
{
    private DbCommand _cmd;
    private DbConnection _conn;
    private DbProviderFactory _factory;

    protected BaseClass()
    {}

    protected BaseClass(string databaseType)
    {
        MessageBox.Show(databaseType);
        ConnectionStringSettings connectionSetting = ConfigurationManager.ConnectionStrings[databaseType];
        MessageBox.Show(connectionSetting.ConnectionString);
        _factory = DbProviderFactories.GetFactory(connectionSetting.ProviderName);
        _conn = _factory.CreateConnection();
        _conn.ConnectionString = connectionSetting.ConnectionString;        
        SetCommand();
    }

    public void SetCommand()
    {
        _cmd = _conn.CreateCommand();
        _cmd.Connection = _conn;
    }

    public void AddParam(string parameterName, object parameterValue)
    {
        DbParameter param = _cmd.CreateParameter();
        param.ParameterName = parameterName;
        param.Direction = ParameterDirection.Input;
        if (parameterValue != null)
        {
            param.Value = parameterValue;
        }
        else
        {
            param.Value = System.DBNull.Value;
        }        
        _cmd.Parameters.Add(param);
    }

    protected DbCommand Command
    {
        get
        {
            return _cmd;
        }
    }

    protected DbProviderFactory Factory
    {
        get
        {
            return _factory;
        }

    }

    protected DbConnection Connection
    {
        get
        {
            return _conn;
        }
    }

    public void Dispose()
    {
        // dispose of the transaction if it exists
        //if (_transaction != null)
        //    _transaction.Dispose();

        // dispose of the connection
        if (_conn != null)
        {
            if (_conn.State == ConnectionState.Open)
                _conn.Close();
            _conn.Dispose();
        }
    }

}

Derived class:

//Copyright : dee-u

using System;
using System.Data;
using System.Data.Common;
using System.Data.SqlClient;
using System.Data.OleDb;
using DataAccess;
using System.Windows.Forms;
//
namespace DataAccess
{
	public abstract class Methods : BaseClass
	{
        protected Methods() : base()
        {}

        protected Methods(string databaseType) : base(databaseType)
        {}

        public void PrepareQuery(string pStmt)
		{
            if ((pStmt == null))
            {
                throw new ArgumentNullException("pStmt");
            }
            if (this.Command.CommandText != pStmt)
            {
                SetCommand();
            }
			this.Command.CommandType = CommandType.Text;
			this.Command.CommandText = pStmt;			
		}

		public double ExecuteActionQuery()
		{
            this.Connection.Open();
            double result = (double)this.Command.ExecuteNonQuery();
            this.Connection.Close();
			return result;
		}			
	
        public bool RecordExists()
		{
            this.Connection.Open();
            IDataReader reader = this.Command.ExecuteReader(CommandBehavior.SingleResult);
			bool result = reader.Read();
			reader.Close();
            this.Connection.Close();
			return result;
		}

		public int RecordCount()
		{
            this.Connection.Open();
            int result = (int)this.Command.ExecuteScalar();
            this.Connection.Close();
			return result;
		}

        public object GetFieldValue()
		{
            this.Connection.Open();
            object result = this.Command.ExecuteScalar();
            this.Connection.Close();
            if (result != null)
            {   
                return result;
            }
            else
            {
			    return string.Empty;
            }
        }

        //overload for ComboBox
        public void PopulateList(ref ComboBox control)
        {
            this.Connection.Open();
            IDataReader reader = this.Command.ExecuteReader(CommandBehavior.SequentialAccess);
            control.Items.Clear();
            while (reader.Read())
            {
                control.Items.Add(reader.GetValue(0));
            }
            reader.Close();
            this.Connection.Close();
        }

        //overload for Listbox    
        public void PopulateList(ref ListBox control)
        {
            this.Connection.Open();
            DbDataReader reader = this.Command.ExecuteReader(CommandBehavior.SequentialAccess);
            control.Items.Clear();
            while (reader.Read())
            {
                control.Items.Add(reader.GetValue(0));
            }
            reader.Close();
            this.Connection.Close();
        }

        public DataSet FillDataSet()
        {
            //DbDataAdapter adapter = Factory.CreateAdapter(this.Command);
            DbDataAdapter adapter = this.Factory.CreateDataAdapter();
            adapter.SelectCommand = this.Command;
            DataSet ds = new DataSet();            
            adapter.Fill(ds);
            return ds;
        }
	}
}

Access:

//Copyright : dee-u

using System;
using DataAccess;
using System.Data;
using System.Data.OleDb;

namespace DataAccess
{	
	public class OleDb : DataAccess.Methods
	{		
        public OleDb() : base("MS Access")
		{				
		}
	}
}

Sample usage:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.Common;
using System.Configuration;
using System.Diagnostics;
using DataAccess.CommonUtilities;
using DataAccess;
using BusinessLogic.CommonFunctions;

namespace ApplicationLayer
{
    public partial class Form1 : Form
    {

        private const string DB_INSERT = "INSERT INTO MyTable(a,b,c,d,e,f) VALUES (?,?,?,?,?,?);";        

        public Form1()
        {
            InitializeComponent();            
        }

        private void button1_Click(object sender, EventArgs e)
        {
            DataAccess.Methods x = new DataAccess.OleDb();                        
            x.PrepareQuery(DB_INSERT);
            x.AddParam("a", "reo'o");
            x.AddParam("b", null);
            x.AddParam("c", 100.000101);
            x.AddParam("d", DateTime.Now.Date);
            x.AddParam("e", true);
            x.AddParam("f", this.pictureBox1);
            if (x.ExecuteActionQuery() != 0)
            {
                MessageBox.Show("DONE!");
            }
            else
            {
                MessageBox.Show("NOT DONE!");
            }          
        }

        private void button2_Click(object sender, EventArgs e)
        {
            DataAccess.CommonUtilities.Access x = new DataAccess.CommonUtilities.Access();            
            x.PrepareQuery("SELECT * FROM MyTable WHERE x = ?");
            x.AddParam("x", 199);
            try
            {
                CommonFunctions.Inform(x.RecordExists().ToString());
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.InnerException.ToString());
            }
            x.PrepareQuery("SELECT Count(a) FROM MyTable WHERE b = ?");
            x.AddParam("b", "rodriguez");
            MessageBox.Show(x.RecordCount().ToString());
        }

        private void button3_Click(object sender, EventArgs e)
        {
            DataAccess.CommonUtilities.Access x = new DataAccess.CommonUtilities.Access();
            //x.BackUpAccessDB(@"C:\dee_u.mdb",@"C:\d.mdb");
            //MessageBox.Show("done");
            x.PrepareQuery("SELECT x FROM MyTable WHERE d = ?");
            x.AddParam("d", DateTime.Now.Date);
            x.PopulateList(ref this.comboBox1);
            x.PopulateList(ref this.listBox1);
        }

        private void button4_Click(object sender, EventArgs e)
        {
            DataAccess.CommonUtilities.Access xx = new DataAccess.CommonUtilities.Access();
            xx.PrepareQuery("SELECT * FROM MyTable");
            DataSet y = xx.FillDataSet();
            MessageBox.Show(y.Tables.Count.ToString());
        }

    }
}

[dee-u]

It's done, check on my sig, thanks for the people who have help me...