php - 无法使用 LIKE 从 Wordpress 数据库获取结果

Question

查询如下

SELECT `sID` FROM `subscribers` where `Email` LIKE '%xxx@xxx.com%'

和

require_once($_SERVER['DOCUMENT_ROOT'].'/wp-load.php');
$hostname = "dd";
$username = "cc";
$password = "aa";
$dbName = "bb";


$conn = new mysqli($hostname, $username, $password);
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 
$conn -> select_db("$dbName") or die( "Unable to select database");

check_subscriber($email, $first, $last, $company, $tablename);
function check_subscriber($email, $first, $last, $company, $tablename)
{
    global $wpdb; 
    $emailid=mysql_real_escape_string($email);
    $subscribercheck = "SELECT `sID` FROM `$tablename` where `Email` LIKE '%$emailid%'";
    $subscriber_exists = "";
    $subscriber_exists = $wpdb -> get_results($wpdb->prepare("$subscribercheck",object));
    var_dump($subscriber_exists);

    if(count($subscriber_exists)>0){
        foreach ($subscriber_exists as $subs)
        {
            echo $sid = $subs-> sID;
        }
    }
    else {
        $wpdb -> insert('subscribers', array(
            'First Name' => $first,
            'Last Name' => $last,
            'Company' => $company,
            'Email' => $email,
            'Date' => date("Y-m-d H:i:s"),
        ));
    }
}

var_dump = NULL

我尝试在我们的数据库中运行查询并且它有效，但它似乎没有在这里运行。请帮忙!

每个变量都已定义。 var_dump = NULL 所以它转到 "else" 子句，其中 wpdb -> Insert 发生并起作用。

$subscriber_exists = $wpdb -> get_results($wpdb->prepare("$subscribercheck",object));

但是，即使我可以在我们的数据库中运行它，也没有给我任何值(value)。

Answer 1

以下是我发现的问题:

• 您正在尝试手动建立数据库连接，而 Wordpress 已经通过 wp-config.php 为您设置好了。删除您用于连接的代码段并使用 $wpdb 对象运行您的查询。
• 您正在使用 $wpdb->prepare() 但您没有正确设置必要的参数。如果你想使用准备好的语句，你需要先了解它们是如何工作的，read here
• 因为您没有使用准备好的语句，所以在没有它的情况下运行您的正常查询。
• 确保您的表位于为 wordpress 设置的同一数据库中。

这就是我重做您的代码的方式:

function check_subscriber($email, $first, $last, $company, $tablename) {
    global $wpdb;

    $email = $wpdb->esc_like($email);

    $query = "SELECT `sID` FROM `$tablename` where `Email` LIKE '%$email%'";

    $subscribers = $wpdb->get_results($query, object);

    if (count($subscribers) > 0) {
        foreach ($subscribers as $subs) {
            echo $sid = $subs->sID;
        }
    } else {
        $wpdb->insert('subscribers', array(
            'First Name' => $first,
            'Last Name' => $last,
            'Company' => $company,
            'Email' => $email,
            'Date' => date("Y-m-d H:i:s"),
        ));
    }
}

但是，如果您真的想使用准备好的语句，请使用:

function check_subscriber($email, $first, $last, $company, $tablename) {
    global $wpdb;

    $query = "SELECT `sID` FROM `$tablename` where `Email` LIKE %s";

    $like_email = '%' . $wpdb->esc_like($email) . '%';

    $subscribers = $wpdb->get_results(
        $wpdb->prepare($query, $like_email),
        object
    );

    if (count($subscribers) > 0) {
        foreach ($subscribers as $subs) {
            echo $sid = $subs->sID;
        }
    } else {
        $wpdb->insert('subscribers', array(
            'First Name' => $first,
            'Last Name' => $last,
            'Company' => $company,
            'Email' => $email,
            'Date' => date("Y-m-d H:i:s"),
        ));
    }
}