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{
  "name": "my-worker",
  "main": "src/index.ts",
  "compatibility_date": "2025-10-11",
  "d1_databases": [
    {
      "binding": "DB",                    // Available as env.DB in your Worker
      "database_name": "my-database",      // Name from wrangler d1 create
      "database_id": "<UUID>",             // ID from wrangler d1 create
      "preview_database_id": "local-db"    // For local development
    }
  ]
}

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Edit the migration file:

```sql
-- migrations/0001_create_users_table.sql
DROP TABLE IF EXISTS users;
CREATE TABLE IF NOT EXISTS users (
  user_id INTEGER PRIMARY KEY AUTOINCREMENT,
  email TEXT NOT NULL UNIQUE,
  username TEXT NOT NULL,
  created_at INTEGER NOT NULL,
  updated_at INTEGER
);

-- Create index for common queries
CREATE INDEX IF NOT EXISTS idx_users_email ON users(email);

-- Optimize database
PRAGMA optimize;

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// src/index.ts
import { Hono } from 'hono';

type Bindings = {
  DB: D1Database;
};

const app = new Hono<{ Bindings: Bindings }>();

app.get('/api/users/:email', async (c) => {
  const email = c.req.param('email');

  try {
    // ALWAYS use prepared statements with bind()
    const result = await c.env.DB.prepare(
      'SELECT * FROM users WHERE email = ?'
    )
    .bind(email)
    .first();

    if (!result) {
      return c.json({ error: 'User not found' }, 404);
    }

    return c.json(result);
  } catch (error: any) {
    console.error('D1 Error:', error.message);
    return c.json({ error: 'Database error' }, 500);
  }
});

export default app;

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migrations/
├── 0000_initial_schema.sql
├── 0001_add_users_table.sql
├── 0002_add_posts_table.sql
└── 0003_add_indexes.sql

{
  "d1_databases": [
    {
      "binding": "DB",
      "database_name": "my-database",
      "database_id": "<UUID>",
      "migrations_dir": "db/migrations",        // Custom directory (default: migrations/)
      "migrations_table": "schema_migrations"   // Custom tracking table (default: d1_migrations)
    }
  ]
}

-- Use IF NOT EXISTS to make migrations idempotent
CREATE TABLE IF NOT EXISTS users (...);
CREATE INDEX IF NOT EXISTS idx_users_email ON users(email);

-- Run PRAGMA optimize after schema changes
PRAGMA optimize;

-- Use transactions for data migrations
BEGIN TRANSACTION;
UPDATE users SET updated_at = unixepoch() WHERE updated_at IS NULL;
COMMIT;

-- DON'T include BEGIN TRANSACTION at start (D1 handles this)
BEGIN TRANSACTION;  -- ❌ Remove this

-- DON'T use MySQL/PostgreSQL syntax
ALTER TABLE users MODIFY COLUMN email VARCHAR(255);  -- ❌ Not SQLite

-- DON'T create tables without IF NOT EXISTS
CREATE TABLE users (...);  -- ❌ Fails if table exists

-- Temporarily disable foreign key checks during schema changes
PRAGMA defer_foreign_keys = true;

-- Make schema changes that would violate foreign keys
ALTER TABLE posts DROP COLUMN author_id;
ALTER TABLE posts ADD COLUMN user_id INTEGER REFERENCES users(user_id);

-- Foreign keys re-enabled automatically at end of migration

// Add to env.d.ts or worker-configuration.d.ts
interface Env {
  DB: D1Database;
  // ... other bindings
}

// For Hono
type Bindings = {
  DB: D1Database;
};

const app = new Hono<{ Bindings: Bindings }>();

// Basic prepared statement
const stmt = env.DB.prepare('SELECT * FROM users WHERE user_id = ?');
const bound = stmt.bind(userId);
const result = await bound.first();

// Chained (most common pattern)
const user = await env.DB.prepare('SELECT * FROM users WHERE email = ?')
  .bind(email)
  .first();

const { results, meta } = await env.DB.prepare(
  'SELECT * FROM users WHERE created_at > ?'
)
.bind(timestamp)
.all();

console.log(results);  // Array of rows
console.log(meta);     // { duration, rows_read, rows_written }

// Returns first row or null
const user = await env.DB.prepare('SELECT * FROM users WHERE email = ?')
  .bind('user@example.com')
  .first();

if (!user) {
  return c.json({ error: 'Not found' }, 404);
}

// Returns the value of a specific column from first row
const count = await env.DB.prepare('SELECT COUNT(*) as total FROM users')
  .first('total');

console.log(count);  // 42 (just the number, not an object)

// For INSERT, UPDATE, DELETE
const { success, meta } = await env.DB.prepare(
  'INSERT INTO users (email, username, created_at) VALUES (?, ?, ?)'
)
.bind(email, username, Date.now())
.run();

console.log(meta);  // { duration, rows_read, rows_written, last_row_id }

// Prepare multiple statements
const stmt1 = env.DB.prepare('SELECT * FROM users WHERE user_id = ?').bind(1);
const stmt2 = env.DB.prepare('SELECT * FROM users WHERE user_id = ?').bind(2);
const stmt3 = env.DB.prepare('SELECT * FROM posts WHERE user_id = ?').bind(1);

// Execute all in one round trip
const results = await env.DB.batch([stmt1, stmt2, stmt3]);

console.log(results[0].results);  // Users query 1
console.log(results[1].results);  // Users query 2
console.log(results[2].results);  // Posts query

// ✅ Insert multiple rows efficiently
const inserts = users.map(user =>
  env.DB.prepare('INSERT INTO users (email, username) VALUES (?, ?)')
    .bind(user.email, user.username)
);
await env.DB.batch(inserts);

// ✅ Fetch related data in parallel
const [user, posts, comments] = await env.DB.batch([
  env.DB.prepare('SELECT * FROM users WHERE user_id = ?').bind(userId),
  env.DB.prepare('SELECT * FROM posts WHERE user_id = ?').bind(userId),
  env.DB.prepare('SELECT * FROM comments WHERE user_id = ?').bind(userId)
]);

// Only for migrations, maintenance, and one-off tasks
const result = await env.DB.exec(`
  SELECT * FROM users;
  SELECT * FROM posts;
`);

console.log(result);  // { count: 2, duration: 5 }

// Single insert
const { meta } = await env.DB.prepare(
  'INSERT INTO users (email, username, created_at) VALUES (?, ?, ?)'
)
.bind(email, username, Date.now())
.run();

const newUserId = meta.last_row_id;

// Bulk insert with batch()
const users = [
  { email: 'user1@example.com', username: 'user1' },
  { email: 'user2@example.com', username: 'user2' }
];

const inserts = users.map(u =>
  env.DB.prepare('INSERT INTO users (email, username, created_at) VALUES (?, ?, ?)')
    .bind(u.email, u.username, Date.now())
);

await env.DB.batch(inserts);

// Single row
const user = await env.DB.prepare('SELECT * FROM users WHERE user_id = ?')
  .bind(userId)
  .first();

// Multiple rows
const { results } = await env.DB.prepare(
  'SELECT * FROM users WHERE created_at > ? ORDER BY created_at DESC LIMIT ?'
)
.bind(timestamp, 10)
.all();

// Count
const count = await env.DB.prepare('SELECT COUNT(*) as total FROM users')
  .first('total');

// Exists check
const exists = await env.DB.prepare('SELECT 1 FROM users WHERE email = ? LIMIT 1')
  .bind(email)
  .first();

if (exists) {
  // Email already registered
}

const { meta } = await env.DB.prepare(
  'UPDATE users SET username = ?, updated_at = ? WHERE user_id = ?'
)
.bind(newUsername, Date.now(), userId)
.run();

const rowsAffected = meta.rows_written;

if (rowsAffected === 0) {
  // User not found
}

const { meta } = await env.DB.prepare('DELETE FROM users WHERE user_id = ?')
  .bind(userId)
  .run();

const rowsDeleted = meta.rows_written;

app.get('/api/users', async (c) => {
  const page = parseInt(c.req.query('page') || '1');
  const limit = parseInt(c.req.query('limit') || '20');
  const offset = (page - 1) * limit;

  const [countResult, usersResult] = await c.env.DB.batch([
    c.env.DB.prepare('SELECT COUNT(*) as total FROM users'),
    c.env.DB.prepare('SELECT * FROM users ORDER BY created_at DESC LIMIT ? OFFSET ?')
      .bind(limit, offset)
  ]);

  const total = countResult.results[0].total as number;
  const users = usersResult.results;

  return c.json({
    users,
    pagination: {
      page,
      limit,
      total,
      pages: Math.ceil(total / limit)
    }
  });
});

const { results } = await env.DB.prepare(`
  SELECT
    posts.*,
    users.username as author_name,
    users.email as author_email
  FROM posts
  INNER JOIN users ON posts.user_id = users.user_id
  WHERE posts.published = ?
  ORDER BY posts.created_at DESC
  LIMIT ?
`)
.bind(1, 10)
.all();

// Transfer credits between users (pseudo-transaction)
await env.DB.batch([
  env.DB.prepare('UPDATE users SET credits = credits - ? WHERE user_id = ?')
    .bind(amount, fromUserId),
  env.DB.prepare('UPDATE users SET credits = credits + ? WHERE user_id = ?')
    .bind(amount, toUserId),
  env.DB.prepare('INSERT INTO transactions (from_user, to_user, amount) VALUES (?, ?, ?)')
    .bind(fromUserId, toUserId, amount)
]);

try {
  const result = await env.DB.prepare('SELECT * FROM users WHERE user_id = ?')
    .bind(userId)
    .first();
} catch (error: any) {
  // D1 errors have a message property
  const errorMessage = error.message;

  if (errorMessage.includes('D1_ERROR')) {
    // D1-specific error
  } else if (errorMessage.includes('D1_EXEC_ERROR')) {
    // SQL syntax error
  } else if (errorMessage.includes('D1_TYPE_ERROR')) {
    // Type mismatch (e.g., undefined instead of null)
  } else if (errorMessage.includes('D1_COLUMN_NOTFOUND')) {
    // Column doesn't exist
  }

  console.error('Database error:', errorMessage);
  return c.json({ error: 'Database operation failed' }, 500);
}

// ❌ DON'T: Single massive INSERT
await env.DB.exec(`
  INSERT INTO users (email) VALUES
    ('user1@example.com'),
    ('user2@example.com'),
    ... // 1000 more rows
`);

// ✅ DO: Break into batches
const batchSize = 100;
for (let i = 0; i < users.length; i += batchSize) {
  const batch = users.slice(i, i + batchSize);
  const inserts = batch.map(u =>
    env.DB.prepare('INSERT INTO users (email) VALUES (?)').bind(u.email)
  );
  await env.DB.batch(inserts);
}

// ❌ DON'T: Fire off many individual queries
for (const user of users) {
  await env.DB.prepare('INSERT INTO users (email) VALUES (?)').bind(user.email).run();
}

// ✅ DO: Use batch()
const inserts = users.map(u =>
  env.DB.prepare('INSERT INTO users (email) VALUES (?)').bind(u.email)
);
await env.DB.batch(inserts);

// ❌ DON'T: Use undefined
await env.DB.prepare('INSERT INTO users (email, bio) VALUES (?, ?)')
  .bind(email, undefined);  // ❌ D1 doesn't support undefined

// ✅ DO: Use null for optional values
await env.DB.prepare('INSERT INTO users (email, bio) VALUES (?, ?)')
  .bind(email, bio || null);

async function queryWithRetry<T>(
  queryFn: () => Promise<T>,
  maxRetries = 3
): Promise<T> {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    try {
      return await queryFn();
    } catch (error: any) {
      const message = error.message;

      // Retry on transient errors
      const isRetryable =
        message.includes('Network connection lost') ||
        message.includes('storage caused object to be reset') ||
        message.includes('reset because its code was updated');

      if (!isRetryable || attempt === maxRetries - 1) {
        throw error;
      }

      // Exponential backoff
      const delay = Math.min(1000 * Math.pow(2, attempt), 5000);
      await new Promise(resolve => setTimeout(resolve, delay));
    }
  }

  throw new Error('Retry logic failed');
}

// Usage
const user = await queryWithRetry(() =>
  env.DB.prepare('SELECT * FROM users WHERE user_id = ?')
    .bind(userId)
    .first()
);

// ✅ Index columns used in WHERE clauses
CREATE INDEX idx_users_email ON users(email);

// ✅ Index foreign keys
CREATE INDEX idx_posts_user_id ON posts(user_id);

// ✅ Index columns used for sorting
CREATE INDEX idx_posts_created_at ON posts(created_at DESC);

// ✅ Multi-column indexes for complex queries
CREATE INDEX idx_posts_user_published ON posts(user_id, published);

-- Check if index is being used
EXPLAIN QUERY PLAN SELECT * FROM users WHERE email = 'user@example.com';

-- Should see: SEARCH users USING INDEX idx_users_email

-- Index only non-deleted records
CREATE INDEX idx_users_active ON users(email) WHERE deleted = 0;

-- Index only published posts
CREATE INDEX idx_posts_published ON posts(created_at DESC) WHERE published = 1;

-- In your migration file
CREATE INDEX idx_users_email ON users(email);
PRAGMA optimize;

await env.DB.exec('PRAGMA optimize');

// ✅ Use specific columns instead of SELECT *
const users = await env.DB.prepare(
  'SELECT user_id, email, username FROM users'
).all();

// ✅ Use LIMIT to prevent scanning entire table
const latest = await env.DB.prepare(
  'SELECT * FROM posts ORDER BY created_at DESC LIMIT 10'
).all();

// ✅ Use indexes for WHERE conditions
// Create index first: CREATE INDEX idx_users_email ON users(email)
const user = await env.DB.prepare('SELECT * FROM users WHERE email = ?')
  .bind(email)
  .first();

// ❌ Avoid functions in WHERE (can't use indexes)
// Bad: WHERE LOWER(email) = 'user@example.com'
// Good: WHERE email = 'user@example.com' (store email lowercase)

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.wrangler/state/v3/d1/miniflare-D1DatabaseObject/<database_id>.sqlite

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npm install drizzle-orm
npm install -D drizzle-kit

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---