How to return a MySQL string from within a PHP function?

Question

I want to reuse the same MySQL query, so thought wrapping it in PHP function might help. I did it as follows:

function fetch_from_db($criteria) {
    global $wpdb;
    $qvar = $wpdb->get_results("select * from $wpdb->terms, $wpdb->term_taxonomy where $wpdb->terms.term_id = $wpdb->term_taxonomy.term_taxonomy_id and $wpdb->term_taxonomy.taxonomy = %s", $criteria);
    return $qvar;
}
$get_two_wheeler_make = fetch_from_db('2-wheeler-make');

but things are not working and it is returning null. How do I make it work? What is wrong in the code?

What happens if you change "select * from $wpdb->terms... into something like: "select * from ".$wpdb->terms.".......? — ThatMSG
– ThatMSG, Commented Apr 28, 2016 at 14:07
@ThatMSG $wpdb->get_results("select * from" . $wpdb->terms, $wpdb->term_taxonomy . "where" . $wpdb->terms.term_id . "=" . $wpdb->term_taxonomy.term_taxonomy_id and $wpdb->term_taxonomy.taxonomy . "=" . $criteria); — Vivek Padhye
– Vivek Padhye, Commented Apr 28, 2016 at 14:15
Dont forget to keep the spaces: $wpdb->get_results("select * from " . $wpdb->terms.", ".$wpdb->term_taxonomy . " where " . $wpdb->terms.term_id . " = " . $wpdb->term_taxonomy.".".term_taxonomy_id." and ".$wpdb->term_taxonomy.taxonomy . " = %s" , $criteria); — ThatMSG
– ThatMSG, Commented Apr 28, 2016 at 14:18
@ThatMSG and does not need double quotes. I geave spaces everywhere else. Now I am getting result back but it is fetching all the result in the table. It doesnt consider $criteria at all that is passed to the function — Vivek Padhye
– Vivek Padhye, Commented Apr 28, 2016 at 14:24

Hexchaimen · Accepted Answer · 2016-04-28 14:51:10Z

1

First, this is a great resource Class Reference $wpdb. The , is making you $criteria the object type being return, not the search criteria; therefore, %s is empty. Add $criteria to the query string. And try again.

$qvar = $wpdb->get_results("SELECT * FROM $wpdb->terms, $wpdb->term_taxonomy
   WHERE $wpdb->terms.term_id = $wpdb->term_taxonomy.term_taxonomy_id
   AND $wpdb->term_taxonomy.taxonomy = '".$criteria."'");

edited Apr 28, 2016 at 14:51

answered Apr 28, 2016 at 14:40

Hexchaimen

3412 silver badges9 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Vivek Padhye Over a year ago

I just inserted plain text instead of $criteria, everything inside quotes, it works perfectly, but the variable is not working

Vivek Padhye Over a year ago

following is working fine

$qvar  = $wpdb->get_results("select * from $wpdb->terms, $wpdb->term_taxonomy where $wpdb->terms.term_id = $wpdb->term_taxonomy.term_taxonomy_id and $wpdb->term_taxonomy.taxonomy = '2-wheeler-make'");

but, instead of that 2-wheeler-make I put $criteria and pass the variable from function then it doesnt work. Otherwise it works even without any hacks

Vivek Padhye Over a year ago

Thank you very much. That last one worked! Yes it should have been handled like a string. Will mark this as correct answer!

Vivek Padhye Over a year ago

for security should I do something about $criteria or does WP_Query handles it?

Hexchaimen Over a year ago

It is always safe to assume the worst. I would look into the wpdb class and see how it is handled. I know get_results() is passed to wpdb query. I would look there.

|

Collectives™ on Stack Overflow

How to return a MySQL string from within a PHP function?

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related