public object wheres(array $cols(string $columns => mixed $value) = array())
参数是键值对, 数据库字段名称 => 字段的值
当参数是空数组时, 函数不会做任何处理
操作成功返回 Object, 失败返回 false
<?php
use Asf\Db\QueryBuilder\Select;
$select = new Select();
$select->cols()
->from('test')
->wheres(array('d' => 1, 'g' => 'hhh'))
->orderBy('id');
// string(92) "[SQL] SELECT * FROM `test` WHERE `d` = ? AND `g` = ? ORDER BY `id` DESC [BVALUES] 1 , hhh"
var_dump($select->show());