C# MySqlHelper

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using MySql.Data.MySqlClient;
using System.Data;
class MySqlHelper:IDisposable
    {
        private MySqlConnection m_conn = null;
        private MySqlTransaction m_trans = null;
        private bool m_tran_enabled = false;


        public MySqlHelper()
        {
            m_conn = new MySqlConnection();
            m_conn.ConnectionString = "Server=localhost;Port=3301;Uid=sa;Pwd=000";
            m_conn.Open();
        }


        public void BeginTrans()
        {
            m_trans = m_conn.BeginTransaction();
            m_tran_enabled = true;
        }


        public void Commit()
        {
            if (m_trans != null && m_tran_enabled)
            {
                m_tran_enabled = false;
                m_trans.Commit();
            }
        }


        public void Rollback()
        {
            if (m_trans != null && m_tran_enabled)
            {
                m_tran_enabled = false;
                m_trans.Rollback();
            }
        }


        public object QuerySome(string sql,int fieldindex)
        {
            using (MySqlCommand cmd = new MySqlCommand(sql, m_conn))
            {
                using (MySqlDataReader sr = cmd.ExecuteReader())
                {
                    if (sr.Read())
                    {
                        return sr.GetValue(fieldindex);
                    }
                }
            }
            return null;
        }


        public delegate void FillValues(MySqlDataReader sr);
        
        public void QuerySomes(string sql, FillValues fill)
        {
            using (MySqlCommand cmd = new MySqlCommand(sql, m_conn))
            {
                using (MySqlDataReader sr = cmd.ExecuteReader())
                {
                    fill(sr);
                }
            }
        }


        public DataTable Source(string sql)
        {
            DataTable dt = null;
            MySqlCommand cmd = null;
            MySqlDataAdapter ad = null;
            try
            {
                lock (dt = new DataTable())
                {
                    cmd = new MySqlCommand(sql, m_conn);
                    ad = new MySqlDataAdapter((MySqlCommand)cmd);
                    dt.Clear();
                    ad.Fill(dt);
                }
            }
            catch (Exception e)
            {
                throw e;
            }
            return dt;
        }


        public void ExecProc(string proc, params MySqlParameter[] ps)
        {
            using (MySqlCommand cmd = new MySqlCommand(proc, m_conn))
            {
                cmd.CommandType = System.Data.CommandType.StoredProcedure;
                foreach (MySqlParameter p in ps)
                {
                    cmd.Parameters.Add(p);
                }
                cmd.ExecuteNonQuery();
            }
        }


        void IDisposable.Dispose()
        {
            m_conn.Close();
            m_conn.Dispose();
            if (m_trans != null)
            {
                m_trans.Dispose();
            }
        }
    }