Combining multiple Wordpress database queries - mysql

Question

Forgive me for re-wording and re-asking this question, but the answers I received a couple weeks back didn't help much...
Basically, I'm looking to somehow combine multiple database queries in Wordpress to retrieve user IDs by searching for term in the 'usermeta' table, but only entries that have a certain 'meta_value'
I'm trying to combine:
$users = $wpdb->get_results("SELECT user_id, meta_value as 'business_name'
FROM $wpdb->usermeta
WHERE meta_key = 'business_name'");
AND:
$users = $wpdb->get_results("SELECT user_id, meta_value as 'business_description'
FROM $wpdb->usermeta
WHERE meta_key = 'business_description'");
To essentially have this:
$users = $wpdb->get_results("SELECT user_id, business_name, business_description
FROM
WHERE
business_name LIKE '%{$keyword}%' OR
business_description LIKE '%{$keyword}%'");
I've looked into INNER JOINs and subqueries, but cannot seem to find a good solution. I realize that I can get away with multiple queries, but this would be searching through possibly thousands of entries, so I'd like to optimize it as much as possible.

Answer 1

Hi #John:
If I understand your question correct (since you gave a technical example of what you were attempting but not a description of what end result you were trying to accomplish I'm not sure) it seems you are doing a user search? If yes, below is what I think you need.
<?php
// Load WordPress, but only for standalone example use
include '../wp-load.php';
// Make sure the database object is available
global $wpdb;
// Get value entered by the user
$keyword = $_GET['keyword'];
// This would be used in your code; the percent would confuse prepare() below
$keyword = "%{$keyword}%";
// Join each meta field as a separate join and reference the meta_key in the join
// prepare() below replaces "%s" with a quoted string value
$sql =<<<SQL
SELECT
users.user_nicename AS user_name,
bizname.meta_value AS business_name,
bizdesc.meta_value AS business_description
FROM
{$wpdb->users} AS users
INNER JOIN {$wpdb->usermeta} AS bizname
ON bizname.user_id=users.ID
AND bizname.meta_key='business_name'
INNER JOIN {$wpdb->usermeta} AS bizdesc
ON bizdesc.user_id=users.ID
AND bizdesc.meta_key='business_description'
WHERE 1=0
OR bizname.meta_value LIKE %s
OR bizdesc.meta_value LIKE %s
SQL;
// User prepare() to avoid SQL injection hacks
$sql = $wpdb->prepare($sql,$keyword,$keyword);
// Finally, get yer results!
$users = $wpdb->get_results($sql);
echo "<ul>";
foreach($users as $user) {
echo "<li>User= {$user->user_name}, Business= {$user->business_name}:{$user->business_description}</li>";
}
echo "<ul>";
The above is a complete working example you can copy to a file in the root of your website and call it something like /test.php allowing you to see it work by using a URL like this:
http://example.com/test.php?keyword=Accounting
Of course, this may be less performant at times than using multiple queries because of the query caching systems built-in to WordPress but it's impossible to tell without some benchmarking.
Hope this helps.
-Mike
P.S. By the way, I'm assuming you were not aware of it but since your prior question evidently hadn't gotten much WordPress love nor had this one I'll mention the WordPress Answers website which is a sister site to StackOverflow. Lots of WordPress enthusiasts are on hand over there to answer WordPress-specific questions.My experience with StackOverflow is they have some of the best developers on the web but few here have specific experience developing with WordPress so you end up with people here trying to answer MySQL questions without knowing the WordPress database schema and without knowing WordPress-specific best practices. Ask over at WordPress Answers and I think you'll an improved quality of answers to your WordPress-specific questions.

Answer 2

Can you post some details on the error messages you are receiving? The SQL here looks ok, but it's impossible to tell what the problem is without seeing the error messages.
For example, are you sure the $keyword field is being populated? How many results to return? Have you tried it without the WHERE statement or just a single OR to troubleshoot? Also, have you tried running this SQL directly on your server with some test keywords?
Give us more of an idea on what you have tried to fix the problem and we'll be able to assist further.
Kind Regards
Luke Peterson