Adding up values inside of a while loop - php

Question

With the first query in the following code I am looking for the checkings made in Berlin under the game number two.
With the second query I want to give points for each of the checkings.
As you will see I am using the function SUM. But let's say that I have 2 checkings and the points for each checking are 50. Well, instead of echoing 100, with this code I echo 5050
What is wrong with it?
Thanks a lot
THE CODE IS CORRECTED AND WORKING, JUST IN CASE SOMEBODY NEEDS IT. Thanks to all
$querya = "SELECT * FROM checkins where gamesid=2 and city='Berlin'";
$resulta = mysql_query($querya) or die(mysql_error());
$sumOfPoints = 0;
while($rowa = mysql_fetch_array($resulta)){
$n = $rowa['venuesid'];
$queryb = "SELECT venuesid, SUM(points) as sumpoints from venues where venuesid='".$n."' GROUP BY venuesid ORDER BY venuesid";
$resultb = mysql_query($queryb) or die(mysql_error());
while($rowb = mysql_fetch_array($resultb)){
$sumOfPoints += $rowb['sumpoints'];
}
}
echo "Total points is $sumOfPoints<br/>";

Answer 1

Some suggestions
Use SUM(points) AS sum (only for clarity when use the sum)
Check that points are numerical fields not varchar.

Answer 2

points must be a string, you need to cast it
SUM(cast(points) as int)
and then follow Gaurav's point about labeling the compute

Answer 3

You're getting 5050 because your script is echoing 50 in two iterations of the loop.
From the looks of it, your second query's GROUP BY clause is not grouping on venuesid when it should be. So, first try changing your GROUP BY clause to:
GROUP BY venuesid
If that doesn't give you the result you're looking for, then you should try running your query directly against the database with a static value for venuesid to see what you get back from it, then perhaps update your question and we can take it from there.