MYSQL - select first 4 records for each category in a table

Question

I have a table INVENTORY that has among other columns CATEGORY and UPDATED. Sorting the table by these columns is easy:

Answer 1

Very much the same as How to limit an SQL result set to not too common items

You could try something like

SELECT  *
FROM    (
            SELECT  *,
                    (   SELECT  COUNT(1) 
                        FROM    INVENTORY 
                        WHERE   CATEGORY = i.CATEGORY 
                        AND     UPDATED < i.UPDATED
                    ) CountTotal
            FROM    @INVENTORY i
        ) sub
WHERE   sub.CountTotal <= 3