问题:

I have a table which stores high-scores, along with player ids. I want to be able to extract a record by a players id, and then get the rank, or position of their score in the table. Means, Basically I want to be able to say "you are in Nth" position, purely based on the players score against all other scores. For Example: if i am at 46th position then to me the position message will be like you are at 46th position out of total scores. Can anyone show me small example?

回答1:

There are two ways of doing it:

Method 1:

SET @i = 0;  SELECT * FROM  scores s1 INNER JOIN (SELECT *, @i := @i + 1 AS rank FROM scores ORDER BY score DESC) AS s2 USING (id);

Method 2:

SELECT *, (SELECT COUNT(1) AS num FROM scores WHERE scores.score > s1.score) + 1 AS rank FROM scores AS s1 ORDER BY rank asc

回答2:

This will provide duplicate rank values when there are duplicates:

SELECT t.playerid,        t.highscore,        (SELECT COUNT(*)           FROM TABLE x           WHERE x.playerid = t.playerid            AND x.highscore >= t.highscore) AS rank   FROM TABLE t  WHERE t.playerid = ?

IE: If three players have the same score for second place, they'll all have a rank value of two.

This will give a distinct value - three players tied for second place, only one will be ranked as 2nd:

SELECT x.playerid,        x.highscore,        x.rank   FROM (SELECT t.playerid,                t.highscore,                @rownum := @rownum + 1 AS rank           FROM TABLE t           JOIN (SELECT @rownum := 0) r       ORDER BY t.highscore DESC) x  WHERE x.playerid = ?

回答3:

Here is an example.

You want to store the user's ID when they log in, like so...

 $_SESSION['username'] = $usernamefromdb;  $_SESSION['id'] = $userid;

And then you want to open a session on every page on yoru website that you will be pulling dynamic information depending on the $_SESSION['id']

 session_start();

Then find the row of data in the datebase according to the userID

 $userid = $_SESSION['id'];  $rank_query = "SELECT * FROM table_name WHERE id='$userid'";  $rank_result = mysqli_query($cxn, $rank_query) or die("Couldn't execute query.");  $row = mysqli_fetch_assoc($rank_result)

Then using PHP, declare the nth postiion as a variable. And pull the total amount of rows from the DB

$rank = $row['rank']; $all = $numrows = mysqli_num_rows($result);

echo out the players rank.

echo $rank . "out of" . $all;

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