I have to draw the ER diagram of library management base on these following requirements:
"The library has books, CDs, tapes, and so forth, which are lent to library patrons. The latter have accounts, addresses, and so forth. If a patron is a minor, she/he must have one sponsoring patron who will be responsible for paying any penalties incurred by the minor. Information must be recorded to identify items that are overdue. Each type of items (tapes, CD, books, etc.) for loan has its own loan period, and penalty rate for overdue loans. Include in your E-R diagram information about keys and constraints if any.
You should come up with 2 different ER diagram, i.e., with and without the IsA construct. Which one would you prefer? Justify your preference, in comparing the database schemas into which ER diagrams may be converted."
There are what I've done, but I'm not sure they are correct or not.
can anyone check over for me and give me some ideas about the constraints between entities?