循环访问多个SQL查询？

Question

我想通过我的数据库循环，只处理100行，准时，否则我的内存将耗尽。

但我的问题是，我不知道，为什么我的脚本没有增加开始和结束的限制。所以我只得到一个回报，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。

有没有人看到我的失败？

$count_values = mysqli_num_rows($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：（检查无极限让所有行的量）

$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); 

问候和感谢！

Answer 1

限制语法是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，但会在循环的第二次迭代中选择200行，因为第二次迭代中的$end = 200和第三次迭代中的300行等等。

并按照kalrodan的规定，您的代码会生成无限循环。

我在代码中做了几个更正。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