PHP/SQL，减少查询次数 - PHP/SQL, Reduce number of queries

PHP/SQL, Reduce number of queries

本文关键字：查询 SQL PHP | 更新日期: 2023-09-27

我在php中查询一个大数据库，但我做得还不够好。我有我需要的代码，我只是找不到压缩这些语句的好方法。

    $q = $_GET['q'];
    (dbinit)
    $query = "SELECT post_id FROM wp_postmeta WHERE meta_key = '_billing_email' AND meta_value = '$q'";
    $result = mysql_query($query);
    while ($row = mysql_fetch_array($result))
{
$thing = $row['post_id'];
$querys = "SELECT 'meta_value' FROM wp_postmeta WHERE post_id = '$thing' AND meta_key = '_order_number'";
$results = mysql_query($querys);
$rows = mysql_fetch_array($results);
$postid = $rows['meta_value'];
$queryss = "SELECT post_id FROM $table WHERE meta_value = $postid AND meta_key = '_order_number'";
$resultss = mysql_query($query);
$rowss = mysql_fetch_array($result);
$order_id = $rowss['post_id'];
(handling)
}

我想知道是否有更有效的方法来进行这些查询，或者将它们放在一个查询中？

不确定$table来自哪里。

但这种JOIN尝试应该有效：

$q = $_GET['q'];
// ... dbinit ...
$query = "SELECT wpp.post_id,
       wpp1.meta_value as orderNumber,
       wpp2.post_id as orderId
    FROM wp_postmeta wpp
    LEFT JOIN wp_postmeta wpp1 
    ON wpp1.post_id = wpp.post_id 
      AND wpp1.meta_key = '_order_number'
    LEFT JOIN $table wpp2
    ON  wpp2.meta_value = wpp1.meta_value 
      AND wpp2.meta_key = '_order_number'
    WHERE wpp.meta_key = '_billing_email' 
      AND meta_value = '$q'";
$result = mysql_query($query);
while ($row = mysql_fetch_array($result)) {
    (handling)
}

正如你所看到的，你可以得到

$thing = $row['post_id'];
$order_id = $row['orderId'];

如果需要的话，在循环内。