[PHP] menu alphabet

$sql = 'SELECT * FROM table WHERE LEFT(nom,1) = "'.mysql_real_escape_string($_GET['lettre']).'" ORDER BY nom';

$sql = 'SELECT * FROM table WHERE LEFT(nom,1) = "'.mysql_real_escape_string($_GET['lettre']).'"';

<a href="page.php?lettre=a">[A]</a> <a href="page.php?lettre=b">[B]</a> <a href="page.php?lettre=c">[C]</a> ... <a href="page.php?lettre=z">[Z]</a>

<?php
mysql_connect();
mysql_select_db();

$sql = 'SELECT * FROM table WHERE LEFT(nom,1) = "'.mysql_real_escape_char($_GET['lettre']).'"';
$req = mysql_query($sql);

while($ligne = mysql_fetch_assoc($req)) {
    echo $ligne['nom'].'<br />';
}
?>