Check mysqli result if row already exists - php

Question

I'm trying to check if a row exist in my db like this:
$uid = $_GET['queryString'];
if(isset($_GET['queryString'])) {
echo "New: ".$uid."<BR>";
$query = "SELECT * FROM stuff WHERE $uid";
// Escape Query
$queryE = $db->real_escape_string($query);
$results = $db->query($queryE);
if(($results->num_rows) > 0) {
echo "NO!";
}
else
{
echo "Make new row";
}
}
else
{
echo 'Error!';
}
But I keep getting the error: Trying to get property of non-object in ....
So if it exist I do one thing, if it doesn't I do the other, i've been searching for about an hour to find the cause, maybe I'm mixing up old PHP4 with my PHP5 stuff?
I've tried a lot, tried some examples but tend to get the error: mysql_fetch_array() expects parameter 1 to be resource, string given
Or should I check it in the query itself?

Answer 1

What line is the error on?!
If it is on the real_escape_string line, you haven't instantiated $db properly.
If it is on the $results->num_rows line, try changing
$results = $db->query($queryE); to:
if(!($results = $db->query($queryE))) {
echo 'Make new row';
} else {
// user likely exists, check $results
}
Also, you need to clean up the way you check the query string -- just process the query variable you want, rather than the whole string. Suggest also to use a different name for the query variable and the table column.