Mysqli query returns an emptry string

Question

I'm dealing with an issue where the mysqli library in PHP doesn't seem to return a longtext column. I can get the value of the column using both console and PHPMyAdmin but mysqli returns nothing but an empty string.

Here's the function I'm using:

public function greetings_get() {
        $output = array();
        $greetings_query = "SELECT `engagement_data`.`data`, `engagement_users`.`name` FROM `engagements`, `engagement_data`, `engagement_users` WHERE `engagements`.`promo_slug` = 'stod2.hm2013' and `engagements`.`user_fbid` = `engagement_users`.`fbid` and `engagement_data`.`engagement_id` = `engagements`.`id` ORDER BY RAND() LIMIT 0,5";
        $greetings = $this->db_connection->prepare($greetings_query);
        $greetings->execute();
        $greetings->bind_result($gr_data, $gr_name);
        while ($greetings->fetch()) {
                $output[] = array('message' => $gr_data, 'name' => $gr_name);
        }
        return $output;
}

In this case, $gr_data is an empty string, while $gr_name returns a value. –Strange isn't it?

Is there something I'm doing wrong?

Please, for the love of future generations; use explicit `JOIN`s — Kermit, Jan 17 '13 at 16:57
Why not use exceptions or `die()` to read what mysqli has to say about the error? — samayo, Jan 17 '13 at 17:07
what if to use http://php.net/manual/en/mysqli-stmt.get-result.php instead of [ugly] binding? — Your Common Sense, Jan 17 '13 at 17:09
Look at these questions http://stackoverflow.com/q/10335278/1741542, http://stackoverflow.com/q/6972319/1741542 — Olaf Dietsche, Jan 17 '13 at 17:09
I can't use get_result in this case because the server I'm using doesn't have mysqlnd installed. — aldavigdis, Jan 17 '13 at 17:14
Ouch! In this case I wouldn't use prepared statements at all. Consider using [my library](https://github.com/colshrapnel/safemysql/blob/master/safemysql.class.php) then. As a bonus, the code of your function become a one-liner `return $this->db->getAll("SELECT ...");` — Your Common Sense, Jan 17 '13 at 17:20

score 3 · Accepted Answer · answered Jan 17 '13 at 17:14

According to this answer at php.net, you must use mysqli_stmt::store_result before you bind the result

When using prepare to prepare a statement to retrieve LOBs the method order matters. Also, method 'store_result()' must be called and be called in correct order. Failure to observe this causes PHP/MySQLi to crash or return an erroneous value.

This

$greetings->execute();
$greetings->store_result();
$greetings->bind_result($gr_data, $gr_name);

should fix it.

Thank you so much -- that took so long to fix. – Will Sewell Feb 22 '13 at 04:50 — Will Sewell, Feb 22 '13 at 04:50

Mysqli query returns an emptry string

1 Answers1