PHP/MySQL - Incrementing variable name to loop for data

Question

I have rows in my teams table named player1, player2, player3 ... player12. In PHP script i set them as variables ($player1,$player2...) and want to loop through them to check if they are NULL, and if they are not to count them.

How may I increment a variable in PHP? I have tried doing it likes this:

<?
    $playerspicked = 0;
    for($i = 1; $i <= 12; $i++) {
        $playercheck = "$player"+$i;
        if($playercheck != 0) {
            $playerspicked++;
        }
    }
?>

but this wouldn't work.

Normalize your data, and then you wouldn't need to use such a dirty solution — Mark Baker
– Mark Baker, Commented Aug 31, 2017 at 20:29
I mean structure your database tables.... having numbered column names is generally an indication that you should be using a separate table with a row for each player — Mark Baker
– Mark Baker, Commented Aug 31, 2017 at 20:52
A schema like that is a huge violation of the Zero, One or Infinity Rule of database normalization. If you created a proper relational table this would be trivial. I'd strongly recommend redoing your schema before trying to solve this problem: You'll only fossilize this really awkward design. — tadman
– tadman, Commented Aug 31, 2017 at 21:15
Oh, I probably gave way too little details and got misunderstood. In table named teams there are teams added by users. Player1, 2 etc are just kind of settings, user can pick up to 12 members for his sport team from a predefined list. I'm not storing multiple players data in a single row :-) — Damian Doman
– Damian Doman, Commented Aug 31, 2017 at 21:18

GrumpyCrouton · Accepted Answer · 2017-08-31 20:21:31Z

3

You can do this with complex expressions (curly brackets {}) around a variable name.

if(empty(${"player$i"})) {
    //player$i is empty
}

complex expressions allow you to set variable names dynamically.

To help you better understand how these work, I will show you that you can also use these just like regular string concatenation like so

$variable = "many test";
echo "this is a test echo. {$variable}";

I commonly use this for generating a variable for many array variables based on their key

$array = array("key1" => "value1", "key2" => "value2");
foreach($array as $key => $value) {
    ${$key} = $value;
}

The code above would create 2 variables, $key1 and $key2, with the appropriate value associated with them.

Alternatively, I'm pretty sure you can just add another $ to the front of your variable, but I would say this is harder to read and figure out what's going on.

$playercheck = "player"+$i;  
if($$playercheck != 0) {
    $playerspicked++;
}

edited Aug 31, 2017 at 20:21

answered Aug 31, 2017 at 20:14

GrumpyCrouton

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1 Comment

Damian Doman Over a year ago

Thanks for sharing these methods, they are of much help!

Clement Hamon · Accepted Answer · 2017-08-31 20:23:21Z

1

In your case there is a much easier way to count all the not null players in the team.

echo count(array_filter($yourTeam));

the array_filter function without a second parameter will automatically remove the null entries.

answered Aug 31, 2017 at 20:23

Clement Hamon

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1 Comment

Damian Doman Over a year ago

That seems really simple and effective as well. If I have some more rows in my $team table, for example two that are not players, all I have to do is decrease the count() by 2 with simple arithmetic?

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