php导出excel 大数据 时候需要注意的问题

 /**

     * 构造函数

     */

    function __construct(){

        parent::__construct();

        $this->check_page();

        $this->control   = 'admin-2016-yyyl3';

        $this->arr_table = array(

            1 => 'yyyl_order'

        );

       load_config('admin/onload');

        load_model('admin/common');

        $this->model = new CommonModel('dmz_act_2016');

    }

//导出excel

    public function saveCSV(){

        header("Content-type:text/html;charset=utf-8");

        ini_set('display_errors', 'Off');

         ini_set('max_execution_time', '3000');                                       
// 就是这里需要手动改变下php.ini中的运存的大小和超时时间的长短

         ini_set('memory_limit', '1024M');

        error_reporting(0);

        $t = (int) $_GET['t'];

        if($t == 3){

            $con = mysql_connect("10.21.2.192", "game", "game");

            mysql_select_db("dmz_act_basic_2016", $con);

            $sql = "set names utf8";

            mysql_query($sql);

            $search_where = " select * from yyyl_order";

            $ret_mysql    = mysql_query($search_where);

            $ret          = array();

            while($row = mysql_fetch_array($ret_mysql)){

                $arr_item             = array();

                $arr_item['account']  = $row['account'];

                $arr_item['uin']      = $row["uin"];

                $arr_item['zone_id']  = $row['zone_id'];

                $arr_item['username'] = $row['username'];

                $arr_item['age']      = $row['age'];

                $arr_item['sex']      = $row['sex'];

                $arr_item['email']    = $row['email'];

                $arr_item['phone']    = $row['phone'];

                $arr_item['qq']       = $row['qq'];

                $arr_item['model']    = $row['model'];

                $ret[]                = $arr_item;

                //var_dump("ddd");

            }

            $header = array(

                'account'  => '账号',

                "uin"      => "UIN",

                'zone_id'  => "大区ID",

                "username" => "昵称",

                "age"      => "年龄",

                "sex"      => "性别",

                "email"    => "邮箱",

                "phone"    => "手机号",

                'qq'       => 'QQ',

                'model'    => '机型'

            );

            $data   = array_merge($headers = array($header), $ret);

            load_library('php-excel');         //  加载phpexcel库

            $xls = new Excel_XML('UTF-8', false, '预约有礼' . $t);

            $xls->addArray($data);

            ob_flush();

            flush();

            $xls->generateXML('jzsn-' . date('YmdHis'));

            exit();

        }

        $where   = "where table_name=yyyl_order";

        $rows    = $this->model->get_list('Information_schema.columns', $where, 'column_name,column_comment');

        $headers = array();

        foreach($rows as $row){

            if($row['column_name'] = "prize_id"){

                $view1['fields'][$row['column_name']] = "奖品序号";

            }

            $header[] = !empty($row['column_comment']) ? $row['column_comment'] : $row['column_name'];

        }

        $where  = "";

        $fields = "*";

        if($t == 4 && isset($_GET['num'])){

            $prize_type = (int) $_GET["num"];

            $where      = "where prize_type = $prize_type";

        }

        $rows = $this->model->get_list($this->arr_table[$t], $where, $fields);

        $data = array_merge($headers = array($header), $rows);

        load_library('php-excel');

        $xls = new Excel_XML('UTF-8', false, '预约有礼' . $t);

        $xls->addArray($data);

        ob_flush();

        flush();

        $xls->generateXML('jzsn-' . date('YmdHis'));

        exit();

    }