Question

我想循环访问我的数据库，只能按时处理100行，否则我的RAM会耗尽。

但我的问题是，我不知道，为什么我的脚本不会增加开始和结束限制。因此，我只获得一次返回，并且不会通过将开始和结束限制增加+100来循环访问我的数据库。

有人看到我的失败吗？

$count_values = mysqli_num_rows($values_gk);
$count_values = intval($count_values);
$myfile = fopen("httpdocs/wp_all_import.txt", "a");

if($values_gk === FALSE){
    fwrite($myfile, "SQL Error\n");
}

$start = -100;
$end = 0;

do{
$start = $start + 100;
$end = $end + 100;

if($end > $count_values){
    $end = $count_values;
}

$values_gkw = $database_gk->query("SELECT `ID` FROM `fWR6qIN_posts` where post_type = 'product' AND post_status = 'publish' limit $start, $end");

fwrite($myfile, "Entered 1. While Loop\n");

while($row = $values_gkw->fetch_assoc()){

    if($row["ID"] != null){
        //do something with the values
        //code removed to reduce the text here
    }
}

fwrite($myfile, "\n+++ Start: " .$start. " Limit: " .$end. " +++\n\n");

} while ($end <= $count_values);

计数值:(无限制地检查以获取所有行的数量）

$values_gk = $database_gk->query("SELECT `ID` FROM `fWR6qIN_posts` where post_type = 'product' AND post_status = 'publish'");
$count_values = mysqli_num_rows($values_gk);
$count_values = intval($count_values);

问候，谢谢！

Answer 1

限制语法为LIMIT offset, count NOT LIMIT offset_start, offset_end。它将在循环的第一次迭代中选择100行，但在第二次循环迭代中将选择200行，在第二次迭代中选择$end = 200，在第三次迭代中选择300行，依此类推。 / p>

根据kalrodan的规定，您的代码会产生无限循环。

我在代码中做了几处更正。试试这个：

$start = -100;
$limit = 100;//constant never changes
$count = 0;
do{
    $start = $start + 100;
    $count = $count + 100;//see changes here

    if($count > $count_values){//see changes here
        $limit = $count_values - $start;//see changes here
    }

    $values_gkw = $database_gk->query("SELECT `ID` FROM `fWR6qIN_posts` where post_type = 'product' AND post_status = 'publish' limit $start, $limit");//$start, $limit here

    fwrite($myfile, "Entered 1. While Loop\n");

    while($row = $values_gkw->fetch_assoc()){

        if($row["ID"] != null){
            //do something with the values
            //code removed to reduce the text here
        }
    }

    fwrite($myfile, "\n+++ Start: " .$start. " Limit: " .$end. " +++\n\n");

} while ($count < $count_values);//condition change here too

循环多个SQL查询？

1 个答案: