/// <summary>
        /// 释放对象占用的所有资源。
        /// </summary>
        public virtual void Dispose()
        {
            if (AutoEnd)
            {
                OnEnd();
            }
            _tableName = null;
            _fields?.Clear();
            _fields = null;
            _whereBefores?.Clear();
            _whereBefores = null;
            _whereExpression?.Clear();
            _whereExpression?.Dispose();
            _whereExpression = null;
            _orderbys?.Clear();
            _orderbys    = null;
            _dataContext = null;

            _parameters?.Clear();
            _parameters = null;

            _dialect = null;
        }
 /// <summary>
 /// 清空where命令列表。
 /// </summary>
 /// <returns></returns>
 public virtual ISelectCommandBuilder WhereClear()
 {
     _whereExpression.Clear();
     return(this);
 }