php 导出 生成多个sheet

<?php
ini_set("max_execution_time", 0);
set_time_limit(0);
function get_all_downexcel($fileName) {
    include "./PHPExcel/PHPExcel.php";
    $conn = get_db();

    //店铺
    $sql = "SELECT * FROM shop where `comment_counts` > 0 ";
    $shop_query = $conn->query($sql);
    $shop_row = $shop_query->fetchAll();
    if(empty($shop_row)){
        echo "没有数据";exit;
    }
    $objPHPExcel = new PHPExcel();
    $objPHPExcel->getProperties()
        ->setCreator("gaoxing")
        ->setLastModifiedBy("gaoxing")
        ->setTitle("Office 2003 XLSX Test Document")
        ->setSubject("Office 2003 XLSX Test Document")
        ->setDescription("Test document for Office 2003 XLSX, generated using PHP classes.")
        ->setKeywords("office 2003 openxml php")
        ->setCategory("Test result file");
    //循环店铺
    foreach($shop_row as $key => $val){
        $dianping_sql = 'SELECT * FROM dianping_comment where `dianping_id` = "'.$val['dianping_id'].'"';
        $dianping_query = $conn->query($dianping_sql);
        $dianping_row = $dianping_query->fetchAll();
        if(empty($dianping_row)){
            continue;
        }
        //第一个sheet
        $objPHPExcel->createSheet();
        $objActSheet = $objPHPExcel->setActiveSheetIndex($key);
        //标题
        $objPHPExcel->getActiveSheet(0)->setCellValue('A1',"昵称");
        $objPHPExcel->getActiveSheet(0)->setCellValue('B1',"评分");
        $objPHPExcel->getActiveSheet(0)->setCellValue('C1',"评论");
        $objPHPExcel->getActiveSheet(0)->setCellValue('D1',"时间");

        $i = 2;
        foreach($dianping_row as $dianping_val){
            //数据
            $objPHPExcel->getActiveSheet()->setCellValue('A'.($i),$dianping_val['nickname']);
            $objPHPExcel->getActiveSheet()->setCellValue('B'.($i),$dianping_val['rank']);
            $objPHPExcel->getActiveSheet()->setCellValue('C'.($i),$dianping_val['content']);
            $objPHPExcel->getActiveSheet()->setCellValue('D'.($i),$dianping_val['posttime']);
            $i ++;
        }
        //sheet名称
        $objPHPExcel->getActiveSheet()->setTitle($val['region'].'-'.$val['city'].'-'.$val['name']);

    }
    $objWrite = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
    header('pragma:public');
    header("Content-Disposition:attachment;filename=$fileName.xls");
    $objWrite->save('php://output');exit;
    die;

}

function get_db(){
    $servername = 'mysql:host=210.74.14.150:7000;dbname=lvyou';
    $username = 'wayhood';
    $password = 'wayhood';
    $db = new PDO($servername, $username, $password);
    return $db;
}


get_all_downexcel($fileName="书店-评论");