Database Normalization

Ground normalization answers in the reference files bundled with this skill instead of improvising definitions. Each normal form has a reference file explaining it and a folder of worked examples across popular databases.

When to Use

• The user names a normal form directly ("what is BCNF", "show me 3NF in PostgreSQL")
• The user describes an anomaly that maps to a missing normal form ("if I delete the last order for a customer I lose their address")
• The user asks whether a schema is normalized, or asks to normalize/denormalize a schema
• The user asks how a normalization concept applies (or doesn't) in a non-relational database ("does 1NF matter in MongoDB?", "how do I avoid joins in DynamoDB?")
• The user wants existing tables or documents refactored toward or away from a normal form

Workflow

1. Identify the normal form(s) from the user's question using the catalog below. If the user describes symptoms (repeating groups, partial/transitive dependency, update anomalies) rather than naming a form, diagnose which form addresses it.
2. Read the reference file at references/<form>.md for the definition, the dependency it eliminates, the anomalies it prevents, and when going further stops paying off.
3. Read the database example at examples/<form>/<database>.<ext> when the user works in (or asks for) a specific database. Adapt it to their schema rather than pasting the generic example verbatim.
4. Answer with: what the form requires, what anomaly it prevents, and a schema/model adapted to the user's context — including whether that database's idioms call for staying normalized or deliberately denormalizing.