Have working sql query... trying to adjust it to use $wpdb

Question

So I have this code that queries a custom plugin generated table in the wp database. It works perfectly as is. But I'm trying to adjust it to use $wpdb instead of the $con function I have set up.

Here is the code that works perfectly, but not using $wpdb:

<?php
$q = strtolower($_GET["q"]);
if (!$q) return;
$isArabic = is_arabic($q);

$con=mysql_connect("localhost","admin","*****");
if($con){
    mysql_select_db("arabic_student",$con);
}
else{
    die("Could not connect to database");
}

mysql_query("SET NAMES utf8");
$sql = "SELECT DISTINCT en_word, ar_word FROM wp_enar_words WHERE en_word LIKE '$q%' OR ar_word LIKE '$q%'";
$rsd = mysql_query($sql) or die(mysql_error());

if($isArabic){

    while($rs = mysql_fetch_array($rsd)) {
        $en_word = $rs['en_word'];
        $ar_word = $rs['ar_word'];

        echo "$ar_word\n";
}
}else{
    while($rs = mysql_fetch_array($rsd)) {
        $en_word = $rs['en_word'];
        $ar_word = $rs['ar_word'];

        echo "$en_word\n";

}
}
?>

Here is my noob attempt to use $wpdb:

global $wpdb;
$sql = $wpdb->get_results("SELECT en_word, ar_word FROM wp_enar_words WHERE en_word LIKE   '$q%' OR ar_word LIKE '$q%'");
$rsd = $wpdb->query('$sql');

But it gets a Fatal error: Call to a member function get_results() on a non-object in.... So maybe missing something obvious but hoping I could get some guidance on how to port my existing code to using $wpdb.

Thanks in advance!

---

UPDATE: so I'm starting to think that the problem is that this code is being called with a jquery plugin. I'm using jquery autocomplete and calling the above php code to populate the form autocomplete:

$("#search_words").autocomplete("<?php bloginfo('template_directory'); ?>/search_ac.php", {});

Could this be the problem? I'm confused because my original code that directly calls the database works perfectly, but once I use $wpdb, it no longer functions

Answer 1

Your error message means that $wpdb in your code is currently pointing to a null pointer. Either WP is not loaded, or you're missing a simple global $wpdb; statement, or both.

If you need to load WP, include wp-load.php.

Or better, in your JS, use ajaxurl:

url = ajaxurl + '?action=youraction'

alongside (assuming the above code):

add_action('wp_ajax_youraction', 'yourcode');

there's an unauthenticated version of the same (see wp-admin/admin-ajax.php)

Answer 2

Try this:

$sql = $wpdb->prepare( "SELECT en_word, ar_word FROM {$wpdb->prefix}enar_words WHERE en_word LIKE '%1\$s%%' OR ar_word LIKE '%1\$s%%'", $q );
$results = $wpdb->get_results( $sql );