Need help to trace the list of DB's used for next 7 days

Hi,

Need help to captured the details of the list of given DB's used and by whome for next 7 days.

i have received the request ,where in the request  says the list of DB's , and they want the details like who are the users uses the DB's for next 7 days.

i Know we can do it with trace, but i woudl like to know, is there any other way , if so can you please give me detailed explanation.

hemadri