TALLMOVE
All arcs

Relational Design

From functional dependencies through the normal forms: why a table splits, and where it stops.

Databases & Data

Start: Functional Dependencies
Progress0/5
  1. 1

    Functional Dependenciesin review

    Data · Relational Design · ~20 min

    A rule about every row a table could hold: test it against the rows, follow what a set of attributes determines, find the candidate keys, and trim the rules to a minimal cover.

  2. 2

    First Normal Formin review

    Data · Relational Design · ~15 min

    One value per cell, and no value spread over numbered copies of a column: find the lists hiding in a table, give each member a row of its own, and name the key that needs.

  3. 3

    Second Normal Formin review

    Data · Relational Design · ~15 min

    A composite key, and an attribute that hangs off only part of it: find the partial dependency, see the rows it makes you repeat, and split it off into a relation of its own.

  4. 4

    Third Normal Formin review

    Data · Relational Design · ~15 min

    A non-key attribute that fixes another: follow each rule's closure, name the chain from the key through it, see the facts it makes you repeat, and synthesize a relation for its middle.

  5. 5

    Boyce-Codd Normal Formin review

    Data · Relational Design · ~20 min

    Every determinant a superkey, no exemption: find the rule third normal form lets through, split on it, chase a tableau to prove the join is lossless, and see which rule the split cannot keep.

  6. laterFourth Normal Form
  7. laterFifth Normal Form
  8. laterDenormalization