How to obtain a relevance score in a table - mysql

Question

I have a mysql table that has typetags for games, like
table game_typetags:
name typetag
--------- --------
game#1 sports
game#1 soccer
game#2 race
game#2 sports
and another table games like
name playcount
--------- ---------
game#1 10
game#2 8
And I want to list relevant games (score them with number of common typetags) and sort with playcount.
So I'm trying to get such an array in PHP:
function getSimilarGames($typetags_array)
{
$pdo->query("SELECT * FROM games COUNT (*) AS ???? ORDER BY games.playcount DESC");
}
So that when I call this function with $typetags = [race,sports] , it should return
name score
____ _____
game#2 2
game#1 1
What query should I use for this?
Thanks !

Answer 1

I do not agree with your database design, you should try to normalize it a bit but here is code that would work on your design:
SELECT games.name, COUNT(1) score
FROM games
INNER JOIN game_typetags ON game_typetags.name = games.name
WHERE game_typetags.typetag IN ('race', 'sports')
GROUP BY games.name
ORDER BY score DESC
I suggest a design like so;
game
-------
id integer pk
name varchar
typetag
-------
id integer pk
tagname varchar
game_typetags
-------
game_id int pk
typetag_id int pk
With this design you join together your tables using ID's instead of using strings everywhere.
A query to get the data you want from this could look like this, note that you could even use the tag-ids to make it tad faster (working on primary key in the database instead of string comparison in the where clause)
SELECT game.id, game.name, game.playcount, COUNT(1) score
FROM game
INNER JOIN game_typetags gtt ON gtt.game_id = game.id
INNER JOIN typetag tt ON tt.id = gtt.typetag_id
WHERE tt.typetag IN ('race', 'sports')
GROUP BY game.id
ORDER BY score DESC

Answer 2

And I figured out a solution to this problem, as follows:
SELECT name, SUM(matches) as relevance_score FROM
(
SELECT
game_typetags.*,
(typetag = 'race' )
+ (typetag = 'sports' )
AS matches
FROM game_typetags HAVING matches>0
ORDER BY matches DESC
) a GROUP BY name ;