database-normalization

A guide to database normalization, a way of organising stored data to reduce duplication and conflicting updates. It covers several recognised levels, from 1NF through 5NF, plus deliberate denormalization.

In plain words
What is it for?
Use it to explain or redesign database tables and documents in systems such as PostgreSQL, MySQL, SQLite, MongoDB, Cassandra, ScyllaDB, and DynamoDB.
Why use it?
It helps identify and fix problems such as changing the same fact in several places or accidentally losing related information when deleting a record.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/cookiemonsterdev/agents-skills/database-normalization
Any agent
npx skills add cookieMonsterDev/agents-skills --skill database-normalization
Clone the repo
git clone --depth 1 https://github.com/cookieMonsterDev/agents-skills

Made for: Claude Code, Codex.

Per session 153 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,652 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00153 $0.01652
Opus 5 $0.00077 $0.00826
Sonnet 5 $0.00031 $0.00330
Haiku 4.5 $0.00015 $0.00165

Measured 2d ago against content hash 3372cb89d7d8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

database-normalization scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

The scan reads SKILL.md. This mod also ships 7 executable files (examples/boyce-codd-normal-form/mongodb.js, examples/denormalization/mongodb.js, examples/fifth-normal-form/mongodb.js, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

architecture-skills/database-normalization/SKILL.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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.

If the user's schema is already anomaly-free at a given form, say so — do not push further normalization for its own sake. Every step past 3NF/BCNF is a judgment call against real anomalies, not a checklist to exhaust.

Normal Form Catalog

Core Forms

The forms nearly every relational schema should reach; each eliminates a specific class of anomaly caused by a specific kind of dependency.

Read the full file on GitHub · 80 lines

Files

What ships with it

57 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 80 lines · 153 tokens per session scan A 3372cb89d7d8

Subscribe to this mod's changes

database-normalization is a skill published in the GitHub repository cookieMonsterDev/agents-skills (4 stars, last pushed 12d ago), licensed MIT. It adds 153 tokens to every session and 1,652 once invoked, about $0.0008 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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