Question

I’m pretty stuck on a Mysql query.
I have a table with three columns;

 user_id | person_id | score.

The table is going to be used to store top 5 highscores for each person.

I need at query that checks if there is less than five rows for a specific person.
Is there is less, insert new row. But if there is five rows I have to replace the lowest score with the new one.

It is for a webservice written in PHP and the data about the new score is posted to the method as params.

Been stuck for some hours now — is it even possible to make this happen in one query ?

Answer 1

You can use stored procedure in mysql. I dont know the names of the tables but if you look closer you will understand how it works.

DELIMITER $$
DROP PROCEDURE IF EXISTS test $$
CREATE PROCEDURE test( IN testparam VARCHAR(22) )
BEGIN
 DECLARE count INT(11);
 SET count = (SELECT COUNT(*) FROM persons );
 IF count < 5 THEN
  insert into table_needed_for_insert values(testparam);
 ELSE
  update table_needed_for_insert where score=(select min(score) from table_needed_for_insert);
 END IF;

 select * from table_needed_for_insert
END $$
DELIMITER;

And how to execute this thing CALL test(1); 1 is the parameter, you can create as many as you need.
And from php you can call directly as like

$result = mysql_query("call test(".$param.")");

And here you can check a tutorial on mysql stored procedures:
http://www.mysqltutorial.org/mysql-stored-procedure-tutorial.aspx