implode() & explode() in arrays - Newbie

Hi I am *trying* to do the following: I have a db that contains categories. I want to select all categories that that have had new activity today, and than send email to the subscribers of those categories. When I look at the array results they are all in one unseparated line. eg: SportFoodDrinkHotels....etc and my call on the database would only give me the results of people with all those categories selected, Eg If I had 2 categories with new activity today, sport and Bio-Tech, it will only give me the email addresses of people with both those categories, whereas I need to choose all email address with Sport OR Bio-Tech OR Sport , [and] Bio-Tech. I thought that I would need to implode () adding a delimiter and then explode() into an array. Here is my code: $sql_cat ="select catname from category where latest_date = '$today' "; $result = @mysql_query($sql_cat) or die(mysql_error()); while ($row =mysql_fetch_array($result)) { $catname = $row["catname"]; $catid = $row["catid"]; $chosen_cat= implode(",", $catname); } $cat_chosen= explode( ",", $chosen_cat); while (list ($va, $cat) = each ($catz)) { echo "<BR>$va $cat"; } echo $cat_chosen; ....and then send email to all with "$cat_chosen" in their chosen categories. It clearly does not work... and I am starting to get in a real mess. I can not work out if it is my method, code or order that I am doing it in that is wrong. If any one can help me onto the right tracks (in newbie terms please) I would really appreciate your knowledge. At the moment I am getting errors with implode statement, and only email addresses of people that have chosen both categories. Many thanks for any light. Cheers James