Query and math

Hi, q1) i got a database with 2 diffrent tables, i want to take out all the information that arent duplicated from on of the tables, like this: $sql = "SELECT t1.rubrik, t1.info, t2.priser FROM table1 AS t1, table2 AS t2 WHERE t1.arkiv = '0' ORDER BY t1.rubrik"; the problem is that i got alot of duplicates (its for another purpose), so i need to filter out the duplicates in the rubrik field to get just one match each, like: id - rubrik - info 0 - aaaa - some info 1 - bbbb - some info 2 - cccc - some info 3 - aaaa - some info 4 - dddd - some info would print out 0 - aaaa - some info 1 - bbbb - some info 2 - cccc - some info 3 - dddd - some info q2) i got like 100 matches from a database into a $num variable, then i want to devide that by 3 aslong as it can be done, eg: while ($num != 0) { ïf ($num / 3 = true){ some code to display some fields from a database $num = $num - 3; } else { some other code to display $num = 0; } } basicly i want the if statement to check if its more then 3 posts left to print out, if not its gonna print out the remaining last 1 - 2 post in a diffrent way (for the looks) regards patrick