SUM, TRUNCATE, IFNULL,left join, left outer join, where, group by, limit

MysqlQuery

	$rs = mysql_query("select p.participant_id, stu_first_name, stu_last_name,
					   SUM(laps_run) as laps,
					   SUM(TRUNCATE(IFNULL(pledge_amt / maxlaps,0),0)) as pledge,
					   SUM(IFNULL(amt_collected,0)) collected
					   from participants as p
					   left join teachers as t on t.teacher_id = p.teacher_id
					   left outer join pledges as pl on pl.participant_id = p.participant_id
					   where pl.teacher_id=$teacher_id
					   group by p.participant_id
					   limit $offset,$rows");