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  • + 0 comments

    When we merge all three tables into one universal relation

    𝑅(name, addr, memberno, description, director, serialno, date) R(name, addr, memberno, description, director, serialno, date) and apply the normal-form rules:

    It clearly has atomic columns → 1NF holds

    There are no partial dependencies on a composite key → 2NF holds

    However, it exhibits a transitive dependency

    (serialno, date) → memberno →(name, addr) (serialno,date)→memberno→(name,addr) where name and addr depend indirectly on serialno and date, violating 3NF’s “no non-key → non-key” rule

    .

    Since it fails 3NF, it cannot be in BCNF.

    Thus, the highest normal form satisfied is 2NF.

  • + 0 comments

    There is a transitive dependency in movies relation, between serial no and Description, hence not in 3NF.

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  • + 1 comment

    This is my process of identifying the normal forms:

    Tables:
    customer(name,addr,MEMBERNO)
    movie(DESCRIPTION,director,serialno)
    borrow(memberno,DATE,SERIALNO)
    
    Determinants:
    memberno -> name,addr
    description -> director,serialno
    serialno,date -> memberno
    serialno -> description
    serialno -> director
    name,addr -> memberno
    
    CKs:
    memberno is CK
    description is CK
    serialno,date is CK
    serialno -> description,director (so serialno is CK)
    name,addr is CK
    

    For 2NF, non-prime attributes must be dependent on CK:

    movie.director: depends on description (is CK) or serialno (is CK)
    borrow.memberno: depends on serialno,date (is CK)
    

    It is in 2NF.

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

    movie.director: depends on serialno, then depends on description (is CK)
    

    It is NOT in 3NF.