Question

I have a query that returns results related to items that match a specific category…

There are 3 mysql tables that results to this, items, categories and item_categories.

These i assume are self explanatory, but the latter, is a linking table that links any specific item to any specific category, using a match of id’s.

The items table contains one row, with an id value of 1.

The categories table is filled with 15 rows, with id values of 1-15.

the item_categories table contains one row, the item_id value is 1 and the category_id value is 5.

This is the mysql query in its php form:

$catResultQuery = "
        SELECT i.id, name, price
        FROM items i
        INNER JOIN item_categories
            ON i.id = item_id
        INNER JOIN categories c
            ON category_id = c.id
        WHERE MATCH (c.id)
        AGAINST ('{$_SESSION['input']}' IN BOOLEAN MODE)
        ORDER BY name
";

The session variable has a value of 5, but for some reason, this query displays a 0 result set.

Even when i run the query in php myadmin, it returns 0 rows.

And i am confused, because in my head, the logic behind all of this seems fairly simple, but for some reason i get 0? Does anyone have any idea where i have gone wrong with this?

Any advice and input would be greatly appreciated, thank you!!

Answer 1

Ok, I see now that you’re building the SQL dynamically. If that’s the case, then this should work:

SELECT i.id, name, price
    FROM items i
    INNER JOIN item_categories
        ON i.id = item_id
    INNER JOIN categories c
        ON category_id = c.id
    WHERE c.id
    IN ('{$_SESSION['input']}')
    ORDER BY name

Just make sure ‘{$_SESSION[‘input’]}’ is comma delimited and be aware that this carries the risk of SQL injection because you’re constructing the SQL on the fly.