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← Normalized Design Part One - Intro to Relational Databases

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Showing Revision 3 created 05/25/2016 by Udacity Robot.

  1. Back in lesson one and two,
    one of the tables in the zoo database we

  2. talked about, was the diet table which
    describes which foods each species eats.
  3. We looked at three ways we could store
    multiple foods, for a single species.
  4. As multiple food columns and
  5. one row per species, as a single
    column with foods separated by commas.
  6. And has separate rows, for
    each food comma species pair and
  7. I mentioned that this form, has some
    big advantages over the other two.
  8. It works better with drawings,
    it works better in comparisons and
  9. you don't have to know in advance how
    many foods there are, and we also looked
  10. at these two tables of donors to
    the zoo and their phone numbers.
  11. In order to avoid duplication,
    we split the information that
  12. was in one object or it's record,
    into two separate tables.
  13. In database jargon,
    these are called normalized forms and
  14. the others are denormalized forms.
  15. Normalization is the central
    idea in database design.
  16. Normalizing involves making
    the relationships among the tables in
  17. your database, match the relationships
    that are really there amongst
  18. the various pieces of data.
  19. There's a bunch of database
    theory behind this idea.
  20. I put a link in the instructor notes to
    a paper with lots of details about it.
  21. Up ahead, I'll just tell you
    the most relevant highlights.