Question

I didn’t want to keep repeating the same select query, so I wrote this function. But it doesn’t work:

function select($what, $table) {
    $query = mysql_query("SELECT $what FROM $table");
}
select(*, products);

Answer 1

1. You need to enclose your arguments in quotes.
2. You should return the query pointer afterwards.
3. You should quote-escape the values to avoid SQL injection.

function select($what, $table) {
    $what = mysql_real_escape_string($what);
    $table = mysql_real_escape_string($table);
    return mysql_query("SELECT '$what' FROM `$table`;");
}
$query = select('*', 'products');

For debugging:

function select($what, $table) {
    $what = mysql_real_escape_string($what);
    $table = mysql_real_escape_string($table);
    $query = mysql_query("SELECT '$what' FROM `$table`;") or die(mysql_error());
    return $query;
}
$query = select('*', 'products');