You could do it the way you are doing it but I would suggest a better way thatis more scalable....
tbl_User
UserId (PK)
Fullname
tbl_AccessLog
AccessLogID (PK)
UserId (FK)
Denied (boolean)
DateTime
Code:
SELECT Count(AccessLogID ) as NumberOfAccesses
FROM tbl_AccessLog
WHERE UserId = 123 and denied = false and datetime=#01/09/2006#
then if you get a 0 count allow access and do a insert like so :
Code:
INSERT INTO tbl_AccessLog (UserId,Denied) VALUES (123,false)
or if you get 1
Code:
INSERT INTO tbl_AccessLog (UserId,Denied) VALUES (123,true)
that way you log all attempts and can set the number off accesses you allow per user and all sorts.
Hope that helps