I have a web site with a membership table (id, lastname, firstname, dateregistered, etc.) and a sessions table (membership id, dateloggedin, etc.) which has a record for each date/time a member has logged into the site. I am trying to determine active members determined by if they have logged into the system within the kast 6 months. I only want to know if they have logged in at least once, I don't want to cound each time they have logged in over the last 6 months. I would like some help on how to write a sql query to give me the results.