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  1. Prepare
  2. Databases
  3. Database Normalization
  4. Database Normalization #7
  5. Discussions

Database Normalization #7

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15 Discussions

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  • elscili444_code
     + 0 comments
    movie(DESCRIPTION,serialno)
description->director,serialno
serialno->description

serial(SERIALNO,director)
serialno->director

customer(name,addr,MEMBERNO)
name,addr -> memberno
memberno -> name,addr

borrow(memberno,DATE,SERIALNO)
serialno,date -> memberno

    1NF valid 2NF valid 3NF valid BCNF <=> A->B were A not CANDIDATE KEY, even though name,addr -> memberno in customer looks invalid by the complementary axiom we have that name, addr is actually a key of customer!

  • myahyamuhaimin
     + 0 comments

    Extending my process of identifying the normal forms here: https://www.hackerrank.com/challenges/database-normalization-6/forum/comments/1225774

    For 3NF, non-prime attributes must be directly dependent on CK, not transitively dependent:

    serial.director: depends on serialno (is CK)
borrow.memberno: depends on serialno,date (is CK)

    It is in 3NF.

    For BCNF, every determinant must be a CK:

    description -> director,serialno (description is CK)
serialno -> description (serialno is CK)
serialno -> director (serialno is CK)
memberno -> name,addr (memberno is CK)
serialno,date -> memberno (serialno,date is CK)
name,addr -> memberno (name,addr is CK)

  • jaydilippatel
     + 0 comments

    3.5 ans

  • vishumnnit
     + 1 comment

    Answer is 3.5

  • swikruthikulal
     + 0 comments

    ANSWER IS 3.5