Combining SqlConnection and SqlCommand in one Class in C#

#define ActivateTransaction
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Reflection;

/// <summary>
/// Summary description for Database
/// </summary>
/// 
namespace CustomDatabase
{
    #region All Enum
    public enum CommandTypeEnum
    {
        /// <summary>
        /// 
        /// </summary>
        Text,
        /// <summary>
        /// 
        /// </summary>
        StoredProcedure
    }

    public enum CommandMode
    {
        NonQuery,
        Scalar,
        Reader
    }
    #endregion

    public class Database : IDisposable
    {
        private string m_sConnectionString;
        private string strSqlCommandText;
        private SqlConnection Conn = null;
        private SqlTransaction oTrans = null;
        private object oScalar;
        List<Parameters> ParameterList = new List<Parameters>();

        public Database()
        {

        }

        protected internal Database(string sConnectionString)
        {
            m_sConnectionString = sConnectionString;
        }

        protected internal string CommandText
        {
            set
            {
                strSqlCommandText = value;
            }
        }

        private string ConnectionString
        {
            get
            {
                return m_sConnectionString;
            }
        }

        /// <summary>
        /// Call or Execute all Reader 
        /// </summary>
        protected internal int ExecuteCommandReader(CommandTypeEnum sqlType, ref DataTable oTable)
        {
            int rowAffected;
            return ExecuteCommand(CommandMode.Reader, sqlType, ref oScalar, out rowAffected, ref oTable);
        }

        protected internal int ExecuteCommandReader(ref DataTable oTable)
        {
            int rowAffected;
            object oScalar = null;
            return ExecuteCommand(CommandMode.Reader, CommandTypeEnum.StoredProcedure, ref oScalar, out rowAffected, ref oTable);
        }

        /// <summary>
        /// Call or Execute all Scalar 
        /// </summary>
        protected internal int ExecuteCommandScalar()
        {
            int rowAffected;
            DataTable oTable = new DataTable();
            return ExecuteCommand(CommandMode.Scalar, CommandTypeEnum.StoredProcedure, ref oScalar, out rowAffected, ref oTable);
        }

        protected internal object ExecuteCommandScalar(ref object eScalar)
        {
            int rowAffected;
            DataTable oTable = new DataTable();
            ExecuteCommand(CommandMode.Scalar, CommandTypeEnum.StoredProcedure, ref eScalar, out rowAffected, ref oTable);
            return oScalar;
        }
        
        /// <summary>
        /// Call or Execute all Non Query 
        /// </summary>
        /// 
        protected internal int ExecuteCommandNonQuery(CommandTypeEnum sqlType, out int nRowsAffected)
        {
            DataTable oDataTable = new DataTable();
            return ExecuteCommand(CommandMode.NonQuery, sqlType, ref oScalar, out nRowsAffected, ref oDataTable);
        }

        protected internal int ExecuteCommandNonQuery(out int nRowsAffected)
        {
            DataTable oDataTable = new DataTable();
            return ExecuteCommand(CommandMode.NonQuery, CommandTypeEnum.StoredProcedure, ref oScalar, out nRowsAffected, ref oDataTable);
        }

        #region ExecuteCommands
        private int ExecuteCommand(CommandMode eMode, CommandTypeEnum sqlType, ref object ScalarOutput, out int nRowsAffected, ref DataTable oTable)
        {
            if (Conn != null)
            {
                if (Conn.State == ConnectionState.Open)
                {
                    using (SqlCommand oCmd = new SqlCommand())
                    {
                        oCmd.CommandText = strSqlCommandText;
                        switch (sqlType)
                        {
                            case CommandTypeEnum.StoredProcedure:
                                oCmd.CommandType = CommandType.StoredProcedure;
                                break;
                            case CommandTypeEnum.Text:
                                oCmd.CommandType = CommandType.Text;
                                break;
                        }
                        foreach (Parameters List in ParameterList)
                        {
                            SqlParameter oParam = new SqlParameter(List.ParameterName, List.ParameterValues);
                            oParam.DbType = List.ParameterType;
                            oCmd.Parameters.Add(oParam);
                        }
                        SqlParameter oRetParam = new SqlParameter("RETURN_VALUE", DBNull.Value);
                        oRetParam.Direction = ParameterDirection.ReturnValue;
                        oCmd.Parameters.Add(oRetParam);
                        oCmd.Connection = Conn;
                        nRowsAffected = 0;
                        switch (eMode)
                        {
                            case CommandMode.NonQuery:
                                nRowsAffected = oCmd.ExecuteNonQuery();
                                break;
                            case CommandMode.Scalar:
                                ScalarOutput = oCmd.ExecuteScalar();
                                break;
                            case CommandMode.Reader:
                                SqlDataAdapter oAdapter = new SqlDataAdapter(oCmd);
                                if (oTable != null)
                                {
                                    oAdapter.Fill(oTable);
                                }
                                break;
                        }
#if ActivateTransaction
                        if (oTrans != null)
                        {
                            oCmd.Transaction = oTrans;
                        }
#endif
                        return Convert.ToInt32(oCmd.Parameters["RETURN_VALUE"].Value);
                    }
                }
                else throw new DataException("Connection not open");
            }
            else throw new DataException("Connection not open");
        }

        #endregion

        protected internal void Open()
        {
            try
            {
                Conn = new SqlConnection();
                Conn.ConnectionString = ConnectionString;
                Conn.Open();
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        /// <summary>
        /// Close the connection to the Sql db
        /// </summary>
        protected internal void Close()
        {
            if (Conn != null)
            {
                Conn.Close();
                Conn = null;
            }
        }

        protected internal void AddParameter(string Name, object value, DbType Type)
        {
            ParameterList.Add(new Parameters() { ParameterName = Name, ParameterType = Type, ParameterValues = value });
        }

#if ActivateTransaction
        /// <summary>
        /// Begins a Transaction
        /// </summary>
        protected internal void BeginTransaction()
        {
            if (Conn != null)
            {
                oTrans = Conn.BeginTransaction();
            }
            else
                throw new DataException("Connection not open");
        }

        /// <summary>
        /// Commits an active transaction
        /// </summary>
        protected internal void CommitTransaction()
        {
            if (oTrans != null)
            {
                oTrans.Commit();
                oTrans = null;
            }
            else
                throw new DataException("Not in transcation");
        }

        /// <summary>
        /// Rollbacks an active transaction
        /// </summary>
        protected internal void RollbackTransaction()
        {
            if (oTrans != null)
            {
                oTrans.Rollback();
                oTrans = null;
            }
            else
                throw new DataException("Not in transcation");
        }
#endif

        #region Connection Dispose
        public void Dispose()
        {
            if (Conn != null)
            {
                Conn.Dispose();
            }
        }
        #endregion
    }

    public class Parameters
    {
        public string ParameterName { get; set; }
        public DbType ParameterType { get; set; }
        public object ParameterValues { get; set; }
    }

}