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SQL statement in WordPress – Phpmyadmin

I’m trying to run an SQL statement on a WordPress page. I’ve already tested it in the phpmyadmin and that works:

SELECT post_id FROM wp_postmeta WHERE meta_value = "9bf2c7f9760393fa83e65ad455e00243"

The result on this is the post_id 20

This is my code in the WordPress template:

<?php
    global $wpdb;
    $uniqueId = $_GET['id'];

    $getPostId = $wpdb->get_var(
        $wpdb->prepare("SELECT post_id FROM " . $wpdb->prefix . "wp_postmeta WHERE meta_value = %d", $uniqueId)
    );
    

    echo $getPostId;
?>

It should echo the value 20, but it does nothing. I’ve also tested if the variable $uniqueId is set and that’s the case.

Tags:

2

Answers


  1. 0

    The %d placeholder in the prepare statement expects an integer. But you are assigning a string. So in this case you should use the string placeholder which is %s.

    New code:

    <?php
    global $wpdb;
    $uniqueId = $_GET['id'];

    $getPostId = $wpdb->get_var(
        $wpdb->prepare("SELECT post_id FROM " . $wpdb->prefix . "wp_postmeta WHERE meta_value = %s", $uniqueId)
    );
    

    echo $getPostId;
?>
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  2. 0

    There are two problems with your code.

    1. You have a typo in your query:

    "SELECT post_id FROM " . $wpdb->prefix . "wp_postmeta WHERE meta_value = %d"

    Should be:

    "SELECT post_id FROM " . $wpdb->prefix . "postmeta WHERE meta_value = %d"

    You’re repeating the wp_ prefix twice:

    ... $wpdb->prefix . "wp_postmeta WHERE ...

    2. As Mike pointed out, %d expects an integer. Your code suggests it should be a string so you should be using %s instead:

    $getPostId = $wpdb->get_var(
    $wpdb->prepare(
        "SELECT post_id FROM " . $wpdb->prefix . "postmeta WHERE meta_value = %s",
        $uniqueId
    )
);

    Updated code:

    <?php
global $wpdb;
$uniqueId = $_GET['id'];

$getPostId = $wpdb->get_var(
    $wpdb->prepare(
        "SELECT post_id FROM " . $wpdb->prefix . "postmeta WHERE meta_value = %s",
        $uniqueId
    )
);

echo $getPostId;
?>
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