92-database

A set of rules for designing database tables and changing their structure over time. It covers Prisma, Drizzle, and SQL files, including names, required fields, indexes, and migrations.

In plain words
What is it for?
Use it when creating or updating schemas, adding relationships or indexes, and preparing database migrations for single-tenant or multi-tenant applications.
Why use it?
It keeps database changes consistent and helps prevent unsafe edits to migrations that may already be deployed.

Cursor rule for Cursor

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 rules/luxvil/ai-coding-rules/92-database
Clone the repo
git clone --depth 1 https://github.com/Luxvil/ai-coding-rules

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 899 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod 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 $0.00000 $0.00899
Opus 5 $0.00000 $0.00449
Sonnet 5 $0.00000 $0.00180
Haiku 4.5 $0.00000 $0.00090

Measured yesterday against content hash 371b5cbab0da, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

92-database 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 yesterday.

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.

Origin

This is a copy

100% identical to 92-database — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.cursor/rules/92-database.mdc · 150 lines

How it starts

The opening of the file, as written. The whole thing — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.

🗃️ Database Rules

Auto-activated for Prisma, Drizzle, and SQL files.

Schema Design

1. Naming Conventions

// ✅ GOOD
model User {
  id        String   @id @default(cuid())
  email     String   @unique
  createdAt DateTime @default(now()) @map("created_at")
  updatedAt DateTime @updatedAt @map("updated_at")

  @@map("users")  // snake_case table name
}

// ✅ Relations: explicit names
model Post {
  author   User   @relation("PostAuthor", fields: [authorId], references: [id])
  authorId String @map("author_id")
}

2. Required Fields (STRICT)

Every table MUST have:

  • id — Primary key (cuid or uuid preferred)
  • created_at — Creation timestamp
  • updated_at — Last update timestamp

For multi-tenant apps:

  • tenant_id — Tenant isolation (CRITICAL)

3. Indexes

// ✅ Index frequently queried fields
model Order {
  id        String @id
  userId    String
  status    String
  createdAt DateTime

  @@index([userId])           // FK queries
  @@index([status, createdAt]) // Filtered queries
}

Migration Rules (STRICT)

1. Never Edit Existing Migrations

# ❌ NEVER modify deployed migrations
# ✅ Create new migration for changes
npx prisma migrate dev --name fix_user_email

2. Reversible Migrations

-- ✅ Always provide rollback
-- Migration: add_status_column
ALTER TABLE orders ADD COLUMN status VARCHAR(20) DEFAULT 'pending';

-- Rollback:
-- ALTER TABLE orders DROP COLUMN status;

3. Data Migrations Separate

migrations/
├── 001_add_status_column.sql  # Schema only
└── 001_backfill_status.ts     # Data migration (separate)

Query Patterns

1. Parameterized Queries (STRICT)

// ✅ ALWAYS use parameterized queries
const user = await prisma.user.findUnique({
  where: { email: sanitizedEmail }
});

// ❌ NEVER concatenate SQL
const query = `SELECT * FROM users WHERE email = '${email}'`; // SQL INJECTION!

2. Select Only Needed Fields

// ✅ GOOD: Select specific fields
const users = await prisma.user.findMany({
  select: { id: true, email: true, name: true }
});

// ❌ BAD: Select all (may include sensitive data)
const users = await prisma.user.findMany();

Read the full file on GitHub · 150 lines

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. yesterday First seen · 150 lines · 0 tokens per session scan A 371b5cbab0da

Subscribe to this mod's changes

92-database is a cursor rule published in the GitHub repository Luxvil/ai-coding-rules (3 stars, last pushed 2d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 899 tokens. A static security scan graded it A with 0 findings. It is 100% identical to 92-database, differing in 0 lines, and is treated as a copy.