Myself I always use a mysql statement as much as I can to filter the data. It's a lot more efficient than selecting a whole table and filtering it yourself with php.
just incorporate the values as variables into your query
$query = "SELECT * FROM my_table WHERE this=that LIMIT $row_offset, $rows";
OR you can only select certain fields as well
$query = "SELECT column1, column2, column4 FROM my_table WHERE this=that LIMIT $row_offset, $rows";
AND you may also skip the offset if you just want the first x rows
moving on...
then store the result
$result = mysql_query($query);
then do whatever with the result set
Hopefully thats what you were talking about