Wordpress SQL JOIN query

Question

Hi Im trying to run 2 querys in the same query call.

        // send the query

global $wpdb;
$commentQ = "SELECT * FROM $wpdb->comments " . $whereClause . $orderBy;
$comments = $wpdb->get_results( $commentQ, ARRAY_A);

So far it works , but when i try to run 2 querys it fails. What I wanna do is i want to run:

**SELECT *
FROM `wp_88_commentmeta`
ORDER BY `wp_88_commentmeta`.`meta_value` ASC
LIMIT 0 , 30**

Im trying to get the meta_value only from that table.

So my question is , how can i call 2 querys in the same call, and if theres i a better way to do that?

EDIT:

I want to JOIN $wpdb->comments with commentmeta. Im only trying to get the field "meta_value".

    global $wpdb;
$commentQ = "SELECT * FROM $wpdb->comments " . $whereClause . $orderBy;
$comments = $wpdb->get_results( $commentQ, ARRAY_A);

// build the string

$commentString = "";
$count = 0;
if( $comments ){
    $first = true;
    foreach( $comments as $row ){
        if( $first ){
            // column labels
            foreach ( $row as $col => $value ){
                    //$commentString .= $col . chr( 9 );

After i join the tables i want to get "meta_value" from wp_commentmeta_88 and insert it instead of "comment_author"

                    // Column Author
                if($col == 'comment_author') {
                $commentString .= 'User Meta        ';
                }           

            // Column IP
            if($col == 'comment_author_IP') {
                $commentString .= '   IP    ';
            }       

            // Column date
            if($col == 'comment_date') {
                $commentString .= '                Datum    ';
            }   

            // Column comment
            if($col == 'comment_content') {
                $commentString .= '                Meddelande   ';
            }                                           

            }
            $commentString .= chr( 13 );
            $first = false;
        }

Answer 1

If you are going to do this is SQL, use a subquery.

SELECT *,
  (SELECT meta_value 
    FROM wp_commentmeta 
    WHERE meta_key = 'your-meta-key' 
    AND wp_commentmeta.comment_id = wp_comments.comment_ID LIMIT 1) as comment_author 
FROM wp_comments

Instead of the *, enumerate the fields you want but leave out comment_author. Obviously, $wpdb functions to keep the table names straight.

Answer 2

Use the MySQL keyword NATURAL RIGHT JOIN

SELECT *  
  FROM table_name1 NATURAL RIGHT JOIN table_name2;

You can add WHERE, ORDER BY too