dependencies - Need further insight on functional depencies -


i'm trying solve below question , need little more insight on functional depend-ices. have goggled , have understanding of it, need further apply understanding.

question:

  • find functional dependencies (includes bijections, one-to-one correspondences, mappings) within tbl 01 ?

here line items tbl 01:

member zip = 2919   membercountycode= ot  zipcountyclass= class1

sorry if format off, when tried paste table in column format lossed.

so far have came this:

{    member zip -> membercounty code    membercountycode -> zipcountyclass }

i'm still bit stumped on bijections , rest of question.

any appreciated.

it hard example. when has use-case specified.

i can give example unf type record cart item this:

cart_item

  • cart_id
  • user_id
  • user_name
  • product_id
  • product_name
  • product_type
  • quantity
  • unit_price

the functional dependency like:

  • product_name, product_type -> product_id
  • user_name -> user_id
  • quantity, unit_price, product_id, user_id -> cart_id

this defined record structure can divided 3 tables: products, users , cart_items. described each record (product, user, cart_items) representing 1 unique record each , prevent duplication/redudancy.

in case, seems both dependency false. why it:

  • one country code can has many zip code
  • one country class can has many country code or zip code

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