# 1. Install
npm install drizzle-orm
npm install -D drizzle-kit

# 2. Configure drizzle.config.ts
import { defineConfig } from 'drizzle-kit';
export default defineConfig({
  schema: './src/db/schema.ts',
  out: './migrations',
  dialect: 'sqlite',
  driver: 'd1-http',
  dbCredentials: {
    accountId: process.env.CLOUDFLARE_ACCOUNT_ID!,
    databaseId: process.env.CLOUDFLARE_DATABASE_ID!,
    token: process.env.CLOUDFLARE_D1_TOKEN!,
  },
});

# 3. Configure wrangler.jsonc
{
  "d1_databases": [{
    "binding": "DB",
    "database_name": "my-database",
    "database_id": "your-database-id",
    "migrations_dir": "./migrations"  // CRITICAL: Points to Drizzle migrations
  }]
}

# 4. Define schema (src/db/schema.ts)
import { sqliteTable, text, integer } from 'drizzle-orm/sqlite-core';
export const users = sqliteTable('users', {
  id: integer('id').primaryKey({ autoIncrement: true }),
  email: text('email').notNull().unique(),
  createdAt: integer('created_at', { mode: 'timestamp' }).$defaultFn(() => new Date()),
});

# 5. Generate & apply migrations
npx drizzle-kit generate
npx wrangler d1 migrations apply my-database --local   # Test first
npx wrangler d1 migrations apply my-database --remote  # Then production

# 6. Query in Worker
import { drizzle } from 'drizzle-orm/d1';
import { users } from './db/schema';
const db = drizzle(env.DB);
const allUsers = await db.select().from(users).all();

npx drizzle-kit studio
# Opens http://local.drizzle.studio

# For remote D1 database
npx drizzle-kit studio --port 3001

# Introspect existing D1 database
npx drizzle-kit pull

# Validate migrations haven't collided
npx drizzle-kit check

import { eq, and, or, like, sql } from 'drizzle-orm';

// Base query
function getUsers(filters: { name?: string; email?: string; active?: boolean }) {
  let query = db.select().from(users).$dynamic();

  if (filters.name) {
    query = query.where(like(users.name, `%${filters.name}%`));
  }
  if (filters.email) {
    query = query.where(eq(users.email, filters.email));
  }
  if (filters.active !== undefined) {
    query = query.where(eq(users.active, filters.active));
  }

  return query;
}

// Usage
const results = await getUsers({ name: 'John', active: true });

import { users } from './schema';

// Insert or ignore if exists
await db.insert(users)
  .values({ id: 1, email: 'test@example.com', name: 'Test' })
  .onConflictDoNothing();

// Insert or update specific fields on conflict
await db.insert(users)
  .values({ id: 1, email: 'test@example.com', name: 'Test' })
  .onConflictDoUpdate({
    target: users.email,  // Conflict on unique email
    set: {
      name: sql`excluded.name`,  // Use value from INSERT
      updatedAt: new Date(),
    },
  });

import { drizzle } from 'drizzle-orm/d1';

// Enable query logging
const db = drizzle(env.DB, { logger: true });

// Custom logger
const db = drizzle(env.DB, {
  logger: {
    logQuery(query, params) {
      console.log('SQL:', query);
      console.log('Params:', params);
    },
  },
});

// Get SQL without executing (for debugging)
const query = db.select().from(users).where(eq(users.id, 1));
const sql = query.toSQL();
console.log(sql.sql, sql.params);

// 35 rows × 3 columns = 105 parameters → FAILS
const books = Array(35).fill({}).map((_, i) => ({
  id: i.toString(),
  title: "Book",
  author: "Author",
}));

await db.insert(schema.books).values(books);
// Error: too many SQL variables at offset

async function batchInsert<T>(
  db: any,
  table: any,
  items: T[],
  chunkSize = 32
) {
  for (let i = 0; i < items.length; i += chunkSize) {
    await db.insert(table).values(items.slice(i, i + chunkSize));
  }
}

await batchInsert(db, schema.books, books);

const D1_MAX_PARAMETERS = 100;

async function autochunk<T extends Record<string, unknown>, U>(
  { items, otherParametersCount = 0 }: {
    items: T[];
    otherParametersCount?: number;
  },
  cb: (chunk: T[]) => Promise<U>,
) {
  const chunks: T[][] = [];
  let chunk: T[] = [];
  let chunkParameters = 0;

  for (const item of items) {
    const itemParameters = Object.keys(item).length;

    if (chunkParameters + itemParameters + otherParametersCount > D1_MAX_PARAMETERS) {
      chunks.push(chunk);
      chunkParameters = itemParameters;
      chunk = [item];
      continue;
    }

    chunk.push(item);
    chunkParameters += itemParameters;
  }

  if (chunk.length) chunks.push(chunk);

  const results: U[] = [];
  for (const c of chunks) {
    results.push(await cb(c));
  }

  return results.flat();
}

// Usage
const inserted = await autochunk(
  { items: books },
  (chunk) => db.insert(schema.books).values(chunk).returning()
);

// Works fine - returns null/undefined when not found
const result = await db.query.table.findFirst({
  where: eq(schema.table.key, 'not-existing'),
});

// Throws TypeError instead of returning undefined
const [result] = await db.batch([
  db.query.table.findFirst({
    where: eq(schema.table.key, 'not-existing'),
  }),
]);
// Error: TypeError: Cannot read properties of undefined (reading '0')

# Create patch with pnpm
pnpm patch drizzle-orm

// In mapGetResult method, add null check:
if (!result) {
  return undefined;
}
if (this.customResultMapper) {
  return this.customResultMapper([result]);
}

// Instead of batch with findFirst, use separate queries
const result = await db.query.table.findFirst({
  where: eq(schema.table.key, key),
});

-- D1 supports this, but Drizzle has no JS equivalent
CREATE TABLE products (
  id INTEGER PRIMARY KEY,
  data TEXT,
  price REAL GENERATED ALWAYS AS (json_extract(data, '$.price')) STORED
);
CREATE INDEX idx_price ON products(price);

import { sql } from 'drizzle-orm';

// Current workaround - raw SQL only
await db.run(sql`
  CREATE TABLE products (
    id INTEGER PRIMARY KEY,
    data TEXT,
    price REAL GENERATED ALWAYS AS (json_extract(data, '$.price')) STORED
  )
`);

// Or in migration file (migrations/XXXX_add_generated.sql)
CREATE INDEX idx_price ON products(price);

// Schema with cascade relationships
export const account = sqliteTable("account", {
  accountId: integer("account_id").primaryKey(),
  name: text("name"),
});

export const property = sqliteTable("property", {
  propertyId: integer("property_id").primaryKey(),
  accountId: integer("account_id").references(() => account.accountId, {
    onDelete: "cascade"  // ⚠️ CASCADE DELETE
  }),
});

// Change account schema (e.g., add a column)
// npx drizzle-kit generate creates:
// DROP TABLE account;  -- ⚠️ Silently destroys ALL properties via cascade!
// CREATE TABLE account (...);

-- Manually rewrite migration to backup related data
PRAGMA foreign_keys=OFF;  -- D1 ignores this, but include anyway

-- 1. Backup related tables
CREATE TABLE backup_property AS SELECT * FROM property;

-- 2. Drop and recreate parent table
DROP TABLE account;
CREATE TABLE account (
  account_id INTEGER PRIMARY KEY,
  name TEXT,
  -- new columns here
);

-- 3. Restore related data
INSERT INTO property SELECT * FROM backup_property;
DROP TABLE backup_property;

PRAGMA foreign_keys=ON;

const upsertSql = sql`insert into ${schema.subscriptions}
  (id, status) values (${id}, ${status})
  on conflict (id) do update set status = ${status}
  returning *`;

// Works fine
const [subscription] = await db.all<Subscription>(upsertSql);

// Throws TypeError: Cannot read properties of undefined (reading 'bind')
const [[batchSubscription]] = await db.batch([
  db.all<Subscription>(upsertSql),
]);

// Use Drizzle query builder instead
const [result] = await db.batch([
  db.insert(schema.subscriptions)
    .values({ id, status })
    .onConflictDoUpdate({
      target: schema.subscriptions.id,
      set: { status }
    })
    .returning()
]);

import { SQLiteSyncDialect } from 'drizzle-orm/sqlite-core';

const sqliteDialect = new SQLiteSyncDialect();
const upsertQuery = sqliteDialect.sqlToQuery(upsertSql);
const [result] = await D1.batch([
  D1.prepare(upsertQuery.sql).bind(...upsertQuery.params),
]);

# Drizzle 1.0 beta generates this:
migrations/
  20260116123456_random/
    migration.sql
  20260117234567_another/
    migration.sql

# But wrangler expects this:
migrations/
  20260116123456_random.sql
  20260117234567_another.sql

npx wrangler d1 migrations apply my-db --remote
# Output: "No migrations found" (even though migrations exist)

// scripts/flatten-migrations.ts
import fs from 'fs/promises';
import path from 'path';

const migrationsDir = './migrations';

async function flattenMigrations() {
  const entries = await fs.readdir(migrationsDir, { withFileTypes: true });

  for (const entry of entries) {
    if (entry.isDirectory()) {
      const sqlFile = path.join(migrationsDir, entry.name, 'migration.sql');
      const flatFile = path.join(migrationsDir, `${entry.name}.sql`);

      // Move migration.sql out of folder
      await fs.rename(sqlFile, flatFile);

      // Remove empty folder
      await fs.rmdir(path.join(migrationsDir, entry.name));

      console.log(`Flattened: ${entry.name}/migration.sql → ${entry.name}.sql`);
    }
  }
}

flattenMigrations().catch(console.error);

{
  "scripts": {
    "db:generate": "drizzle-kit generate",
    "db:flatten": "tsx scripts/flatten-migrations.ts",
    "db:migrate": "npm run db:generate && npm run db:flatten && wrangler d1 migrations apply my-db"
  }
}

npx drizzle-kit generate
tsx scripts/flatten-migrations.ts
npx wrangler d1 migrations apply my-db --remote

// ❌ DON'T: Use traditional transactions (fails with D1_ERROR)
await db.transaction(async (tx) => { /* ... */ });

// ✅ DO: Use D1 batch API
const results = await db.batch([
  db.insert(users).values({ email: 'test@example.com', name: 'Test' }),
  db.insert(posts).values({ title: 'Post', content: 'Content', authorId: 1 }),
]);

// With error handling
try {
  await db.batch([...]);
} catch (error) {
  console.error('Batch failed:', error);
  // Manual cleanup if needed
}

./scripts/check-versions.sh

Checking Drizzle ORM versions...
✓ drizzle-orm: 0.44.7 (latest)
✓ drizzle-kit: 0.31.5 (latest)

{
  "dependencies": {
    "drizzle-orm": "^0.45.1"
  },
  "devDependencies": {
    "drizzle-kit": "^0.31.8",
    "@cloudflare/workers-types": "^4.20260103.0",
    "better-sqlite3": "^12.5.0"
  }
}