<!--商品查询--> 
<input type="text" name="bianhao" value="" maxlength="10" size="10" style="width:100px; margin:0px 0px 0px 25px;height:20px;"/> 
<input type="submit" value="商品编号查询" style="margin:0px 0px 0px 10px;cursor:pointer;background-color:#C30D23;border:0px;color:#FFFFFF;width:85px;border-radius:5px;padding:3px 0;font-size:13px;"/>

public function MallList(){ //写方法
$goods=M('shop_goods_info'); //实例化数据库对应的表
$codes=I('param.bianhao'); //获取前台文本框数据
if(isset($codes) && $codes != ''){
$where['code']=$codes;
$this->assign('codes',$codes); //显示
}
}
$info=$classify->where(array('code'=>$code))->find(); //查询语法

<form action='' method='post'>
文本框:<input type='text' name='text'>
<input type='submit' value='提交',name='sub'>
</form>
<?php
if(!empty($_POST['sub'])){
echo $_POST['text']；
}
?>