hi there.. im a newbie at php and got a probe using the mysql sum. I know how to use it in only one table but if join the table i don't know how to the sample codes ex. this code works cause im only using one table

PHP Code:

$query = "SELECT SerialNumber, SUM(Grade) FROM D03Registrar Where SerialNumber = ". $serial. "  AND RegistrationNumber = '". $_GET['regno'] ."' GROUP BY SerialNumber "; 


but in this code i dont know how to use the sum

PHP Code:

$query = "SELECT d.Code,d.PFinal, d.FFinal, d.Grade,
          d.TeacherName, t.Description,d.Day, d.room, d.time, t.Subject, t.Number, t.Units ".
 "FROM D03Registrar d LEFT JOIN tablenewA3 t  ".
    "ON d.Code = t.CurCode where SerialNumber = ". $serial ." AND RegistrationNumber = '". $_GET['regno'] ."'"; 


thanks for your help..

You need a Group By clause for a SUM to work with multiple fields in the select list.

Just remember that you have to specify in your group by clause every columns you use in the select output.
In your case, it would be something like this:

PHP Code:

$query=<<<SQL
SELECT 
  d.Code,d.PFinal, d.FFinal, sum(d.Grade),d.TeacherName, t.Description,d.Day, d.room, d.time,
  t.Subject, t.Number, t.Units
FROM D03Registrar d 
  LEFT JOIN tablenewA3 t ON d.Code = t.CurCode 
WHERE SerialNumber = {$serial}
AND RegistrationNumber = '{$_GET['regno']}'
GROUP BY d.Code,d.PFinal, d.FFinal, d.Grade,d.TeacherName, t.Description,d.Day, d.room, d.time,t.Subject, t.Number, t.Units
SQL;