PHP and Mysql to much adding data - php

Question

i'm generating random team array.All players are stored in DB without team. I need to assign 20 players from database to a team and get their info into array. I wrote the code, but somehow code assigns 60 players instead of 20 in database. Where did I went wrong?
$Team = array();
$i=0;
while($i < 20)
{
$rand = rand(1,100);
$sql = $con->query("SELECT * FROM players where id='$rand'");
if($sql->num_rows > 0)
{
$data = $sql->fetch_array();
if($data['teamid'] == NULL)
{
$con->query("UPDATE players SET teamid='$teamid' WHERE id='$rand'");
$Team [$i]['name'] = $data['name'];
$Team [$i]['surfname'] = $data['surfname'];
$Team [$i]['rating'] = $data['rating'];
$Team [$i]['position'] = $data['position'];
$i++;
}
}
}

Answer 1

There's a simpler way to do this (forgive me if my SQL or PHP is not exactly correct, it's been a while).
// Generate 20 unique random numbers between 1 and 100
// see https://stackoverflow.com/a/5612704/910328
$randomPlayerIds = range(1, 100);
shuffle($randomPlayerIds);
$randomPlayerIds = array_slice($randomPlayerIds, 0, 20);
// In your query, get 20 records where id is in the list of random numbers AND
// teamid is null, and set results to the team array.
$players = $con->query(
"select * from players where id in $randomPlayerIds and teamid is null"
);
$team = $players->fetch_assoc();
// Update your database.
$teamid = ???; // wherever you're getting this value from
$con->query("UPDATE players SET teamid='$teamid' WHERE id in $randomPlayerIds");

Answer 2

Try this. This assigns 20 people to a team.
$Team = array();
for($i=0;$i<20;$i++)
{
$rand = rand(1,100);
$sql = $con->query("SELECT * FROM players where id='$rand'");
if($sql->num_rows > 0)
{
$data = $sql->fetch_array();
if($data['teamid'] == NULL)
{
$con->query("UPDATE players SET teamid='$teamid' WHERE id='$rand'");
$Team [$i]['name'] = $data['name'];
$Team [$i]['surfname'] = $data['surfname'];
$Team [$i]['rating'] = $data['rating'];
$Team [$i]['position'] = $data['position'];
}
}
}