Ist Normal Form ↩

• Rules:
  • Each attribute contains atomic values:
    • If composite values, make separate coloumns.
    • If multivalued, make separate tuples (or create new table to store multivalued variable values).
  • Each col contains values from same domain.
  • Each col has unique name.
  • No ordering applied to cols nor rows.
• No duplicate rows.

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2nd Normal Form

• Rules:
  • It is in 1NF.
  • No partial dependancy.
    • Partial dependancy is when : Proper subset of Ck -> non-prime attribute
• Decompose R to remove partial dependancy to make it in 2NF. ---

3rd Normal Form

• Rules:
  • It is in 2NF.
  • No transitive dependancy for non-prime attributes.
  • There should be no functional dependancy like : Non-prime attribute -> Non-prime attribute

  • NOTE: AB -> C where A is prime attr, and B is non-prime attr, then AB is considered non-prime attr in above condition.

2NF		3NF
No PD -> NDA		No PD -> NDA
		No NDA -> NDA

• Alternate way to check 3NF:
  • Satisfies either of the following conditions for each of the non-trivial FDs:
    • LHS is Super key
    • RHS is Prime attribute

BCNF

• R is in BCNF iff:
  • It is in 3NF
  • For each non-trivial FD X->Y, X must be a super key.