Database Scheme

Posted By on October 3, 2014


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Basic Structure of realtional Database
Keys

Database Scheme

  1. We distinguish between a database scheme (logical design) and a database instance (data in the database at a point in time).
  2. A relation scheme is a list of attributes and their corresponding domains.
  3. The text uses the following conventions:
    • italics for all names
    • lowercase names for relations and attributes
    • names beginning with an uppercase for relation schemes

    These notes will do the same.For example, the relation scheme for the deposit relation:

    • Deposit-scheme = (bname, account#, cname, balance)

    We may state that deposit is a relation on scheme Deposit-scheme by writing deposit(Deposit-scheme).

    If we wish to specify domains, we can write:

    • (bname: string, account#: integer, cname: string, balance: integer).

    Note that customers are identified by name. In the real world, this would not be allowed, as two or more customers might share the same name.Figure 3.2 shows the E-R diagram for a banking enterprise.

      
    Figure 3.2: E-R diagram for the banking enterprise

  4. The relation schemes for the banking example used throughout the text are:
Basic Structure of realtional Database
Keys

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Posted by Akash Kurup

Founder and C.E.O, World4Engineers Educationist and Entrepreneur by passion. Orator and blogger by hobby

Website: http://world4engineers.com