Hi everyone ..:icon_cheesygrin:
I have these describtion and I want to great ER for :"A bookstore database maintains information about books, professional journals, their authors and publishers. Books and journals are collectively referred to as publications that are published by publishers. All publications have a serial number (ISBN), a title and a year of publication. Books have an edition number whereas journals have a volume and number. No book or journal is published by more than one publisher. Journals contain articles. A book or an article can have one or more authors. Articles have a title and a subject category and no article can appear in more than one journal. Authors have a SSN, name and date of birth, whereas a publisher has a name and address."
and I have few questions :
1-"All publications are characterized by their serial number (ISBN), title, year of publication." (means set the attributes to books and journals ?(because "collectively referred as publication.") ).
2-"A Book or journal can be published by one publisher only. ":is weak entity which is "publisher " ,is it relation 1:N ?because the weak entity is N:1!!
3-"Journals contain articles.":means there is relation name contain to articles?
4- is "year of publication."relation attribute ?
5-"it can appear in only one journal. "is these is N:1?
6-"A book or an article can have more than one author (one or more)."from these the new entity is author , but what is the relations between book ,article and author ?
Please help me...:icon_sad: