PHP/SQL Highscores, avoiding duplicate entries

[Olivier]

As you (probably ) know I'm running some webgames at my website, and they have global highscores. I'd like to get rid of duplicate entires having the same player name. Basically for a given name I'd like to keep the highest score only.

I'm using an SQL database and wanted to know if the comparison/replace stuff can be made directly with the SQL command REPLACE? And if yes how? (I checked the SQL doc and I think the answer is no).
I know I can do it with PHP but it would probably have a higher load on the server as I would have to first read the data, eventually delete a row and then write a new row.

PS: Yes it's rather an easy method assuming each player would use a unique username, but I think setting up a login system would be over complicated.

[Indiepath]

If each player has a unique ID then it's quite simple but you will need to insert a score into the table if the player is not there already.

Code to update :

UPDATE high_score_table
SET score = 'nnn', level = 'nn'
WHERE unique_id = 'user_id'

[Olivier]

AFAIK my players don't have unique IDs. I'd be glad to know how to do it. For the moment I'm simply assuming each player would use a unique name (VARCHAR).

As you guess I'm pretty new to SQL. According to the official doc I could use the INSERT command with the ON DUPLICATE KEY UPDATE statement, that would act like an UPDATE command.
Anyway I think the main problem is comparing the old score with the new one?

[Adam]

I don't think running an extra SQL query on score submission is going to be a big server hit.

Are you trying to stop a user constantly submitting a score from a single play session or are you trying to have one score per player? If you are doing the latter without unique user tracking i think you are going to a lot of trouble just to anoy players.

[Olivier]

I'm just trying to have one score per player. How to track users then?

Would players really be annoyed to see only their highest score listed? Do some players *feel better* after having filled 10 entries in a row?

[Teq]

Why not let them submit multiple times? That way the player has a summary of their progress and for your _main_ scoreboard you can always do something along the lines of

SELECT player, MAX(score) AS m_score FROM score_board GROUP BY player ORDER BY m_score