Partial Dependency

where an attribute in a table depends on only a part of the primary key and not on the whole key.

Normalization

First Normal Form (1NF)

A relational schema is a first normal form (1NF) if:

• domains of all attributes are atomic.
• the value of each attribute contains only a single value from that domain

<aside> 💡 In DBMS, we assume that all the relations are in 1NF, by default.

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Second Normal Form (2NF)

A relational schema is a second normal form (2NF) iff:

• It is in 1NF
• it contains no partial dependency

More

Check if right side has non-prime attribute and left side is a proper subset of candidate key.

Third Normal Form (3NF)

A relation schema R is in third normal form (3NF) if for all:

$α → β ∈ F^+$

at least one of the following holds:

• $α → β$ is trivial (that is, $β ⊆ α$)