I'm sure this has been answered a million times before, but I can't seem to find a clear concinse answer.

I need to do two things.
First I need to get the results from a mysql database and add them together. Example: I need to retrieve the credit worth of several courses a student has taken.
Here is the code I have been trying to use:
[/code]
$getcredits = mysql_query("SELECT credit FROM courseactivity WHERE sid='$sid' GROUP BY grade");
$creditsarray = mysql_fetch_array($getcredits);
$totalcredits = array_sum($creditsarray);
echo "total: ".$totalcredits;
[/code]
The next thing I need to do is take all of the grades the student has gotten and get the average.

I'm stumped and need help...

First you should use an agredate function for doing the first query

SELECT sum(credit) FROM courseactivity WHERE sid='$sid' GROUP BY grade

For the second you should post your table definition