text: /**
   * Created by yangyxu on 8/20/14.
   */
  module.exports = zn.Class({
      properties: {
          config: null,
          pool: null
      },
      methods: {
          init: function (config, ){
              this._config = config;
          },
          beginTransaction: function () {
              return (new Transaction(this._pool)).begin();
          },
          select: function (argv){
              return this.query(zn.sql.select(argv));
          },
          insert: function (argv){
              return this.query(zn.sql.insert(argv));
          },
          update: function (argv){
              return this.query(zn.sql.update(argv));
          },
          delete: function (argv){
              return this.query(zn.sql.delete(argv));
          },
          getConnection: function (){
              throw new Error("The ConnectionPool Class must implement getConnection method.");
          },
          getSqlSchema: function (){
              throw new Error('The ConnectionPool Class must be implement getSqlSchema method.');
          },
          query: function (){
              throw new Error('The ConnectionPool Class must be implement query method.');
          }
      }
  });
  