compare similarity between users PHP [closed]

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Closed 5 years ago.

i'm making a site with a user system and want to match users by their profile which have like 20 fields

i want that users can get a match with an other user when they are above 50% which is 10 fields of the 20 the same

i already got this:

    $query = "SELECT * FROM users WHERE username='test'";
    $result = mysqli_query($db_conx, $query);
    $array = mysqli_fetch_row($result);

    $query2 = "SELECT * FROM users WHERE username='test2'";
    $result2 = mysqli_query($db_conx, $query2);
    $array2 = mysqli_fetch_row($result2);

    $similar = array_intersect($array, $array2);
    $p2_perc = count($similar) / count($array2);

    echo round($p2_perc * 100) . "% equal";

i want that the users will automatically get that specific user displayed but i can fix that

anyone ?

thanks in advance appreciated very much!

the real question is like this

$query2 = "SELECT * FROM users LIMIT 1";
if ($query2 similarity > 50%)
echo "$user2";

Answer 1

You can combine this into one query like this:

SELECT
    user1.username,
    user2.username,
    (
        (user1.row1=user2.row1) + 
        (user1.row2=user2.row2) +
        ...
    )/20 AS score
FROM
    users AS user1,
    users AS user2
WHERE
    user1.username <> user2.username
HAVING
    score > 0.5

This returns the two usernames and their score only it the score is greater than 0.5,

Explanation: The two columns get compared (each of the user1.rowX=user2.rowX). If they're the same, it's 1, else 0. The sum of the 0's and 1's gets divided by the number of questions (20) and this is the score (it's a simple calculation of the average).

But this might get quite slow if you check a lot of users. If you want to display the matches only for a given user (e.g. who is logged in currently) use:

SELECT
    user1.username,
    user2.username,
    (
        (user1.row1=user2.row1) + 
        (user1.row2=user2.row2) +
        ...
    )/20 AS score
FROM
    users AS user1,
    users AS user2
WHERE
    user1.username <> user2.username AND
    user1.username = 'CURRENTLY_LOGGED_IN_USER'
HAVING
    score > 0.5