mysql_query > array

Hi, is it possible to retreive the contents of a query to an array. The reason i ask is because i have a page which shows a list of sytems held in the Systems table. By each system i have a check box and if the user is competent in that system i want to place a tick in it. This data is stored in User_Systems with System_ID and User_ID. So what i would like to do is query the Systems table to get all the systems then query the User_Systems table and get an array of system_ids. Then whilst drawing the table of checkboxes i can check to see if the system_id for that checkbox is in the array... Thanks for your help