MySQL echos only one elemen - php

Question

I've a problem with a MySQL script. The script should echo every element out of the table where "gruppe" is $gruppe. But I am only getting one single output.
<?php
if ( $_SERVER["REQUEST_METHOD"] == 'POST' ) {
$gruppe = $_POST["gruppe"];
$mail = $_POST["mail"];
$betreff = $_POST["betreff"];
$nachricht = $_POST["nachricht"];
if (!empty($nachricht)) {
$sql = new rex_sql;
$sql->debugsql = 0; //Ausgabe Query
$sql->setQuery("SELECT * FROM $db_users WHERE gruppe = '$gruppe'");
for($i=0;$i<$sql->getRows();$i++)
{
$id_mail = $sql->getValue("id");
$mail_mail = $sql->getValue("email");
$ausgabe_mail = $mail_mail;
$sql->next();
}
}
}
?>
<?php echo $ausgabe_mail ?>

Answer 1

Your echo-statement is outside the loop. The loop fetches all email addresses, one by one, and stores them in $mail_mail and $ausgabe_mail. Each iteration of the loop overwrites the previous contents of both variables.
After the loop ends, you echo the last value of $ausgabe_email.
Retry with the echo inside the loop:
<?php
if ( $_SERVER["REQUEST_METHOD"] == 'POST' ) {
$gruppe = $_POST["gruppe"];
$mail = $_POST["mail"];
$betreff = $_POST["betreff"];
$nachricht = $_POST["nachricht"];
if (!empty($nachricht)) {
$sql = new rex_sql;
$sql->debugsql = 0; //Ausgabe Query
$sql->setQuery("SELECT * FROM $db_users WHERE gruppe = '$gruppe'");
for($i=0;$i<$sql->getRows();$i++) {
$id_mail = $sql->getValue("id");
$mail_mail = $sql->getValue("email");
$ausgabe_mail .= ',' . $mail_mail;
$sql->next();
}
echo $ausgabe_mail;
}
}
?>
EDIT: as clarified, expanded the example with string concatenation and moved the echo outside the loop again.