public static class SqlHelper    {        /// 
        /// EF SQL 语句返回 dataTable        /// 
        /// ef数据上下文        /// 语句        /// 参数        /// 
             public static DataTable SqlQueryForDataTatable(this Database db, string sql, SqlParameter[] parameters=null)        {            MySqlConnection conn = new MySqlConnection();            conn.ConnectionString = db.Connection.ConnectionString;            if (conn.State != ConnectionState.Open)            {                conn.Open();            }            MySqlCommand cmd = new MySqlCommand();            cmd.Connection = conn;            cmd.CommandText = sql;            if (parameters!=null && parameters.Length > 0)            {                foreach (var item in parameters)                {                    cmd.Parameters.Add(item);                }            }            MySqlDataAdapter adapter = new MySqlDataAdapter(cmd);            DataTable table = new DataTable();            adapter.Fill(table);            return table;        }    }