Cloudflare D1 Database Skill

Auto-Discovery Skill for Claude Code CLI

Complete knowledge domain for working with Cloudflare D1 - serverless SQLite database on Cloudflare's edge network.

---

Auto-Trigger Keywords

Claude will automatically suggest this skill when you mention any of these keywords:

Primary Triggers (Technologies)

• d1
• d1 database
• cloudflare d1
• wrangler d1
• d1 migrations
• d1 bindings
• sqlite workers
• serverless database cloudflare
• edge database
• d1 queries
• sql cloudflare

Secondary Triggers (Commands & Patterns)

• wrangler d1 create
• wrangler d1 migrations
• prepared statements d1
• batch queries d1
• d1 api
• d1 schema
• d1 indexes
• sqlite cloudflare workers
• sql workers api
• database bindings cloudflare

Error-Based Triggers

• "D1_ERROR"
• "D1_EXEC_ERROR"
• "D1_TYPE_ERROR"
• "D1_COLUMN_NOTFOUND"
• "statement too long"
• "too many requests queued"
• "DB's isolate exceeded its memory limit"
• "DB exceeded its CPU time limit"
• "Network connection lost"
• "cannot start a transaction within a transaction"

---

What This Skill Does

• ✅ Creates D1 databases with wrangler CLI
• ✅ Manages SQL migrations (create, list, apply)
• ✅ Configures D1 bindings in wrangler.jsonc
• ✅ Writes type-safe D1 queries in Workers
• ✅ Handles prepared statements with parameter binding
• ✅ Optimizes performance with batch queries
• ✅ Creates indexes for faster queries
• ✅ Implements error handling and retry logic
• ✅ Provides CRUD operation patterns
• ✅ Supports local and remote development workflows

---

Known Issues Prevented

---

Token Efficiency

Manual D1 Setup (Without Skill):

• Create database: 800 tokens
• Configure bindings: 600 tokens
• Write migrations: 1,200 tokens
• Implement queries: 2,000 tokens
• Add error handling: 800 tokens
• Create indexes: 600 tokens
• Total: ~6,000 tokens

With cloudflare-d1 Skill:

• Reference skill templates: 1,500 tokens
• Customize for your use case: 1,000 tokens
• Total: ~2,500 tokens

Savings: ~58% token reduction (3,500 tokens saved)

---

When to Use This Skill

✅ Use When:

• Building Cloudflare Workers that need relational data
• Storing user data, content, or application state
• Need SQL queries with JOINs and complex filtering
• Migrating from MySQL/PostgreSQL to edge database
• Building multi-tenant applications (per-user databases)
• Need ACID transactions and data consistency

❌ Don't Use When:

• Simple key-value storage needed → Use KV instead
• Large file/blob storage → Use R2 instead
• Real-time collaborative state → Use Durable Objects instead
• Need MySQL/PostgreSQL compatibility → Use Hyperdrive
• Embedding/vector search → Use Vectorize instead

---

Quick Usage Example

# Create database
npx wrangler d1 create my-app-db

# Create migration
npx wrangler d1 migrations create my-app-db create_users_table

# Apply migration
npx wrangler d1 migrations apply my-app-db --local

// Query from Worker
const user = await env.DB.prepare('SELECT * FROM users WHERE email = ?')
  .bind('user@example.com')
  .first();

---

File Structure

~/.claude/skills/cloudflare-d1/
├── SKILL.md                        # Complete D1 documentation
├── README.md                       # This file (auto-trigger keywords)
├── templates/
│   ├── d1-setup-migration.sh      # Complete workflow script
│   ├── schema-example.sql         # Production-ready schema
│   └── d1-worker-queries.ts       # TypeScript query examples
└── reference/
    ├── query-patterns.md          # All D1 API methods
    └── best-practices.md          # Performance & security tips

---

Dependencies

• Required: cloudflare-worker-base skill (for Worker setup)
• CLI: wrangler@4.43.0+
• Types: @cloudflare/workers-types@4.20251014.0+

---

Related Skills

• cloudflare-worker-base - Base Worker + Hono setup
• cloudflare-kv - Key-value storage (simpler than D1)
• cloudflare-r2 - Object storage for files
• hono-routing - Advanced Hono patterns

---

Learn More

• SKILL.md: Complete D1 documentation with examples
• templates/: Working code templates for common patterns
• reference/: Deep-dive guides for query optimization

---

Status: Production Ready ✅ Last Updated: 2025-10-21 Maintainer: Jeremy Dawes (Jezweb)