使用 fputcsv() 函数将 12,000 条记录从 mysql table 写入 csv 文件时出现内存和文件大小问题

Question

我有一个包含 12,000 条记录的数据库，我想将这些记录写入 csv 文件，我在 php 代码下尝试过，但在文件大小变为 980kb 后，数据开始删除，此后文件大小开始减小。已成功从 mysql table 获取数据。 csv 文件写入问题。请在下面查看我的代码。

<?php
include './connection.php';

set_time_limit(0);
ini_set('memory_limit', '1024M');
$connection;
$db_link;

    $output_file = "db_data.csv";

    try {

        $csv_file = fopen($output_file,"b");
        $value = array('Name','Address','Phone Number','International Phone Number','Website');
            if(!empty($value)){
                fpassthru($csv_file);
                fputcsv($csv_file, $value,',');
                fclose($csv_file);
            }       
    } catch (Exception $e) {
        echo $message = $e->getMessage();
    }



        $connection = new Connection('1.2.3.8','admin','pass','automtn');
        $db_link = $connection->connect();
        $low = 0;
        $high = 100;
        $query = "SELECT name,formatted_address,formatted_phone_number,international_phone_number,website "
                . " FROM `fetch_data` ORDER BY id ASC LIMIT $low OFFSET $high";

        while($result = mysqli_query($db_link,$query)){
            $data = array();
            while ($row = mysqli_fetch_row($result)) {                
                $data[] = $row;                
            }
            write_to_csv($data);
            unset($data);
            $low+=100;
            $high+=100;
            $query = "SELECT name,formatted_address,formatted_phone_number,international_phone_number,website "
                . " FROM `fetch_data` ORDER BY id ASC LIMIT $low OFFSET $high";

        }

function write_to_csv($results) {

    global $output_file;
    $row = 0;
    try {

        $csv_file = fopen($output_file,"b");

        $fetched_data = $results;
        unset($results);
        foreach ($fetched_data as $value) {
            if(!empty($value)){
                fpassthru($csv_file);
                fputcsv($csv_file, $value, ',');
            }            
        }
        fclose($csv_file);
        unset($fetched_data);
    } catch (Exception $e) {
        echo $message = $e->getMessage();
    }
}


?>

Answer 1

您每次都在写入文件的开头。坦率地说，我很惊讶模式 "b" 本身不会抛出错误；除非文档已过时。

使用附加模式写入"a"（或"ab"）

$csv_file = fopen($output_file,"ab");

既然你要保留一个全局文件名，为什么不给自己省点麻烦而保留一个全局文件句柄呢。您不必在每次写入时都花时间打开和关闭文件。

Answer 2

问题出在我的低逻辑上，我用 $limit 更改了它，它将保持不变，$offset 每次递增 100，现在工作正常

<?php
include './connection.php';

set_time_limit(0);
ini_set('memory_limit', '1024M');
$connection;
$db_link;

    $output_file = "db_data.csv";

    try {

        $csv_file = fopen($output_file,"a+");
        $value = array('Name','Address','Phone Number','International Phone Number','Website');
            if(!empty($value)){
                fpassthru($csv_file);
                fputcsv($csv_file, $value,',');
                fclose($csv_file);
            }       
    } catch (Exception $e) {
        echo $message = $e->getMessage();
    }



        $connection = new Connection('1.2.3.8','admin','pass','automtn');
        $db_link = $connection->connect();
        $limit = 100;
        $offset = 0;

        $query = "SELECT name,formatted_address,formatted_phone_number,international_phone_number,website "
                . " FROM `fetch_data` ORDER BY id ASC LIMIT $limit OFFSET $offset ";

        while($result = mysqli_query($db_link,$query)){
            $data = array();
            while ($row = mysqli_fetch_row($result)) {                
                $data[] = $row;                
            }
            write_to_csv($data);
            unset($data);

            $offset +=100;
            $query = "SELECT name,formatted_address,formatted_phone_number,international_phone_number,website "
                . " FROM `fetch_data` ORDER BY id ASC LIMIT $low OFFSET $offset ";

        }

function write_to_csv($results) {

    global $output_file;
    $row = 0;
    try {

        $csv_file = fopen($output_file,"a+");

        $fetched_data = $results;
        unset($results);
        foreach ($fetched_data as $value) {
            if(!empty($value)){
                fpassthru($csv_file);
                fputcsv($csv_file, $value, ',');
            }            
        }
        fclose($csv_file);
        unset($fetched_data);
    } catch (Exception $e) {
        echo $message = $e->getMessage();
    }
}


?>

使用 fputcsv() 函数将 12,000 条记录从 mysql table 写入 csv 文件时出现内存和文件大小问题

Memory and File size issue with writing 12,000 records from mysql table to csv file using fputcsv() function

php

file-io

fopen

fclose

fputcsv