MySQL Search Function Not Working with Foreign Key Relations

Other Questions MySQL
1

I’m having trouble with a search feature in my PHP application. I have two database tables that are connected through foreign keys.

Here’s my table structure:

tb_products
id (AI)  |   model  |  brand_id  |  description
---------------------------------------------
  1      |   X100   |    1       |  item1
  2      |   X200   |    3       |  item2
  3      |   X300   |    2       |  item3
  4      |   X400   |    3       |  item4

tb_brands
id (AI)  |  name
----------------
  1      |  Sony
  2      |  LG
  3      |  HP

I built a CRUD interface that shows products with search functionality. The search works fine for most fields, but when I try to search by brand name (like “Sony” or “HP”), it doesn’t return the right results because the products table stores brand_id numbers instead of actual brand names.

Here’s my current search query:

$query = "SELECT *
            FROM tb_products p, tb_brands b
            WHERE
                model LIKE '%".@$_POST['model']."%' AND
                (p.brand_id=b.id AND b.name LIKE '%".@$_POST['brand']."%') AND
                description LIKE '%".@$_POST['description']."%'
            ORDER BY model
    ";

When I search for “HP”, I get this result:

      3      |   X300   |    2       |  item3

It seems like the search is finding HP (which has id 3) but showing the wrong product record. How can I fix this query to show the correct results when searching by brand name?

2

Your WHERE clause logic is the problem. When you use comma-separated tables without clear conditions, MySQL creates a cross join and you get unexpected product records. I ran into this same issue building a product catalog. Move your join condition p.brand_id=b.id to an explicit JOIN clause instead. Try this: ```php
$query = “SELECT p.id, p.model, p.brand_id, p.description, b.name as brand_name
FROM tb_products p
INNER JOIN tb_brands b ON p.brand_id = b.id
WHERE
p.model LIKE '%”.$_POST[‘model’].“%’ AND
b.name LIKE '%”.$_POST[‘brand’].“%’ AND
p.description LIKE '%”.$_POST[‘description’].“%’
ORDER BY p.model”;

3

totally agree! mixing joins can really mess things up in MySQL. stick to explicit JOINs like FROM tb_products p INNER JOIN tb_brands b ON p.brand_id = b.id and itll fix those weird results. also, make sure ur WHERE conditions are clear too!

4

You’re getting a cartesian product from implicit joins. Your current query structure mixes up the join conditions and creates weird results. Hit this same issue working on an inventory system last year. Switch to explicit JOIN syntax instead of comma-separated tables: ```php
$query = “SELECT p.*, b.name as brand_name
FROM tb_products p
JOIN tb_brands b ON p.brand_id = b.id
WHERE
p.model LIKE '%”.@$_POST[‘model’].“%’ AND
b.name LIKE '%”.@$_POST[‘brand’].“%’ AND
p.description LIKE '%”.@$_POST[‘description’].“%’
ORDER BY p.model”;

This clearly defines how the tables connect and fixes the confusion. Also, use prepared statements instead of jamming POST data directly into the query - you're wide open to SQL injection right now. Explicit JOINs make everything cleaner and way more reliable.
5

Had this exact headache building a parts lookup system for our warehouse. You’re mixing old comma joins with modern WHERE conditions, which confuses MySQL about which brand goes with which product. I fixed it by switching to LEFT JOIN instead of INNER JOIN - especially useful if you’ve got products without brands assigned. Also, use table aliases consistently in your WHERE clause. You’re doing p.brand_id but then just model without the prefix. When column names overlap, MySQL picks the wrong table. Your current setup will return duplicate rows too, so test with different search terms to make sure you get unique results.