1

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 :-)

  • the or die( mysql_error() ); is bad, in newer versions of WordPress and PHP the mysql extension isn't even used ( the mysql extension and all the mysql_ functions are deprecated in favour of mysqli, you should avoid them ). Instead check the value of $results and check for an error value – Tom J Nowell Mar 18 '15 at 14:51
4

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.

  • I think I made a mistake in my thinking. I have the wp_postmeta table filled with different page attributes. I want to extract all other page attributes where the group is $group. So basically filter all pages that have the group $group. – Interactive Mar 18 '15 at 14:11
  • @Interactive What you're looking for sounds like a WP_Query, one second let me write it up. Another option is you could use the $post_id's that get returned from that SQL to then get_post(). Finally, another option is to modify the main query by using pre_get_posts. You may be better off creating a new question and explaining your problem then show what you've tried to solve it ( you code above ). – Howdy_McGee Mar 18 '15 at 14:25
  • 1
    This answer to »getting all values for a custom field key (cross-post)« offers an ready-made function for the $wpdb call, which can be customized for your use. @Interactive On a second thought, its not exactly what you want, but maybe helpful anyway. – Nicolai Mar 18 '15 at 14:32
  • Thank you so much for your answers and time. In the meantime I used get_post like you suggested. What would be wiser? Use the get_post or use your WP_Query? – Interactive Mar 18 '15 at 14:32
  • 1
    @Interactive probably WP_Query - it's more powerful and it makes less DB calls, sounds what you're looking for - getting the actual posts. – Howdy_McGee Mar 18 '15 at 14:34

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