database design for tracking the location. NEED HELP!! :(

im currently doing the database design for an android app like friend finder. im doing the coding in java and i'l be using google maps to display the location. location is tracked using gps. the functionality would be:

-locate u n all ur friends on the map

-give alerts when a friend is somewhere close like within 5km

-hide users location from certain people.

this is what ive come up with so far..

location

----------

location id

location name



user

---------

user id

and rest of the details



friendlist

------------

userid

friendid

distance_frm_user

users_location [visible, nt visible]

type [friend, rejected]

if the user accepts a friend request then 2 rows r created in the friendlist table

one with userid=1 and friendid=2

second with userid=2 and friendid=1

and the attribute "type" in the friendlist wud be set to friend for both the rows in the friendlist table.

users_location is set to visible if the user wants that friend to see his location.

my questions are:

-do i need to a map entity if yes then what would be the relation between the map entity and the location entity?

-do i need to provision users_location in the location table? if yes i dnt have a clue hw i can do that.

-are the tables correct? or am i forgetting something.



P.S: This is the first time im doing this.