can a user visit the same library more than once in any one day?
presumably a user cannot visit the same library more than once in any time slice..
what you have in tblvisits is an intersection table (where an entity represents the intersection of two other tables)
often intersection tables are used where two things overlap eg when placing and order you will have what is in effect an intersection table storing the orderno and the product number + any other associated elements which are relevant to that intersection .. for an order that would be say quantity ordered, agreed price any discounts and so on). usually the priamry key of an intersection table are the foreign keys that comprise the primary key other tables for our order thats usually the order no + product no
if it was me then I'd model the priamry key of the sub table to be the library + user + dateofvisit
bear in mind that Access/JET stores date time values so you don't need visit_date and satrt tiem and end time. you need two elements, which coudl be
date/time of arrival and date/time of departure
date/time of arrival and duration of visit
userage ignores one of the fundamentals of db design as the age is only relevant for that day or fro the remainder of that (birth)year. what you shoudl be recording is DateOfBirth and calculate the age from that.
address arguably should be in a separate table as a person may have more than one address, although it may be that your business rules allow a single address. if that is so then you need to qualify that when you document/comment your project. a library by definition may have only one address (at least I hope there isn't a library out there with two different addresses.
Im not to certain whether username is a user name such as "moss2076" or a persons name such as "Mr Stirling Moss", if the latter then it would be better to store all elements as separate columns
qualifications (optional but some people insist that their qualifications are registered)
and optionally known as.. some people may prefer to be called, say Billy Bragg, rather than William Bragg.
I'd rather be riding on the Tiger 800 or the Norton