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deema
Starting Member
2 Posts |
 Posted - 2006-01-31 : 07:31:30
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| Hi, I’ve three questions, would someone answer them please, I have 3 entities: The book entity(BookNo,BookNmae,AuthorName,Price...etc), the MembershipCard entity(CardNo,MembershipNo,ClientNo,PublishDate,EmpNo..etc), and the Client entity(ClientNo,ClientName,ClientAddr,ClientPhoneBookNo,RequiredBookNo,..etc) 1-What is the relationship degree between them, is it ternary or binary?and Why?I'm so confused ,my answer is ternary, I made a (1:m) relationship between the clients entity and the books entity (a client may buy more than one book), (1:m) relationship between the employee entity and the books entity (an employee may sell more than one book)and a (1:m) relationship between the employee and the Client(an employee may serve more than one client(is it right or it's (M:N)). So is my answer is right or wrong, please help me to understand, I’m so confused. 2- Is the cardinality degree between the Client entity and the book entity , (0,N) for the client entity and (1:N) for the book entity?? 3-What is the best model to use in designing data in general,Chen's model or Crow's Foot and why?I think it's Crow's one ,for it's more arranged and easy to read. with thanks deema |
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Frank Kalis
Constraint Violating Yak Guru
413 Posts |
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X002548
Not Just a Number
15586 Posts |
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deema
Starting Member
2 Posts |
Posted - 2006-01-31 : 13:47:35
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quote]Originally posted by Frank KalisHave you considered quote:
Originally posted by Frank Kalisposting to the comp.databases.theory newsgroup?
sorry,I don't know where is this site.
quote:
Originally posted by X002548Wow, if this isn't homework, I don't know what is....Brett
It's a part from a long H.w ,but we have to search the right answer from any where,I did part of it but I need to know if it,T or F.Thanks for your help. |
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X002548
Not Just a Number
15586 Posts |
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blindman
Master Smack Fu Yak Hacker
2365 Posts |
Posted - 2006-01-31 : 17:27:08
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| God forbid impressionable youngs minds should be prematurely exposed to THAT! |
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Arnold Fribble
Yak-finder General
1961 Posts |
Posted - 2006-01-31 : 18:01:30
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| I'm having real trouble working out what bits of the original posting were the question and what parts were the attempt to answer it.I mean, what on earth is PublishDate doing in the middle of MembershipCard, or RequiredBookNo in Client? Why does a fourth entity (employee) suddenly appear halfway through (1)? |
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Frank Kalis
Constraint Violating Yak Guru
413 Posts |
Posted - 2006-02-01 : 03:01:41
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quote:
sorry,I don't know where is this site.
Point your newsreader to dp-news.maxwell.syr.edu and then subscribe to comp.databases.theory. The regulars there should have enough time to help you out.--Frank KalisMicrosoft SQL Server MVPhttp://www.insidesql.deHeute schon gebloggt? http://www.insidesql.de/blogs |
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Entities design