C# tool class MySqlHelper for operating MySQL

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();  
            }  
        }  
    }