Get data from database using $WPDB

Question

I'm missing something here.
I simply want to get data from my database. So I tried this but keeps giving me an error.

global $wpdb;
$sql = "SELECT * FROM $wpdb->postmeta WHERE group='$group'";
$results = $wpdb->get_results($sql) or die(mysql_error());

foreach( $results as $result ) {

    echo $result->company_name;

}

$group is a parameter passed in the url the variable is $group = $_GET['group'];

This is the error:

WordPress database error: [You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'group='bicyclegroup'' at line 1] SELECT * FROM xx_postmeta WHERE group='thegroup' You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'group='thegroup'' at line 1

Can somebody please help me fix this once and for all so I can save it locally and use it for further projects :-)

Answer 1

It may be because group doesn't exist in the postmeta table. Your meta_key is probably called group and has a meta_value of bicyclegroup. This is assuming you haven't modified the postmeta table. What you could try is:

$sql = "SELECT * FROM $wpdb->postmeta WHERE meta_key = 'group' AND meta_value='$group'";

This will return:

• meta_id
• post_id
• meta_key ( group )
• meta_value ( bicyclegroup )

---

Another option is to get all posts by post meta is a secondary query WP_Query. To do so would look like this:

$test_posts = new WP_Query( array(
    'post_type'      => 'post',
    'posts_per_page' => -1,
    'meta_key'       => 'group',
    'meta_value'     => $group
) );

<?php if( $test_posts->have_posts() ) : ?>

    <?php while( $test_posts->have_posts() ) : $test_posts->the_post(); ?>

        <h1><?php the_title(); ?></h1>
        <?php the_content(); ?>

    <?php endwhile; ?>

<?php endif; ?>

I'm not sure if you're using post are your post type so change that field accordingly.