Vercel Postgres

Existing database

Meet Drizzle

Get Started with Drizzle and Vercel Postgres in existing project

This guide assumes familiarity with:

dotenv - package for managing environment variables - read here
tsx - package for running TypeScript files - read here
Vercel Postgres database - read here
Vercel Postgres driver - read here & GitHub

Basic file structure

This is the basic file structure of the project. In the src/db directory, we have table definition in schema.ts. In drizzle folder there are sql migration file and snapshots.

📦 <project root>
 ├ 📂 drizzle
 ├ 📂 src
 │   ├ 📂 db
 │   │  └ 📜 schema.ts
 │   └ 📜 index.ts
 ├ 📜 .env
 ├ 📜 drizzle.config.ts
 ├ 📜 package.json
 └ 📜 tsconfig.json

Step 1 - Install required package

npm

yarn

pnpm

bun

npm i drizzle-orm @vercel/postgres dotenv
npm i -D drizzle-kit tsx

yarn add drizzle-orm @vercel/postgres dotenv
yarn add -D drizzle-kit tsx

pnpm add drizzle-orm @vercel/postgres dotenv
pnpm add -D drizzle-kit tsx

bun add drizzle-orm @vercel/postgres dotenv
bun add -D drizzle-kit tsx

Step 2 - Setup connection variables

Create a .env file in the root of your project and add your database connection variable:

POSTGRES_URL=

warning

It’s important to name the variable POSTGRES_URL for Vercel Postgres.

In the Vercel Postgres storage tab, you can find the .env.local tab and copy the POSTGRES_URL variable

Step 3 - Setup Drizzle config file

Drizzle config - a configuration file that is used by Drizzle Kit and contains all the information about your database connection, migration folder and schema files.

Create a drizzle.config.ts file in the root of your project and add the following content:

import 'dotenv/config';
import { defineConfig } from 'drizzle-kit';

export default defineConfig({
  out: './drizzle',
  schema: './src/db/schema.ts',
  dialect: 'postgresql',
  dbCredentials: {
    url: process.env.POSTGRES_URL!,
  },
});

Step 4 - Introspect your database

Drizzle Kit provides a CLI command to introspect your database and generate a schema file with migrations. The schema file contains all the information about your database tables, columns, relations, and indices.

For example, you have such table in your database:

CREATE TABLE IF NOT EXISTS "users" (
	"id" integer PRIMARY KEY GENERATED ALWAYS AS IDENTITY (sequence name "users_id_seq" INCREMENT BY 1 MINVALUE 1 MAXVALUE 2147483647 START WITH 1 CACHE 1),
	"name" varchar(255) NOT NULL,
	"age" integer NOT NULL,
	"email" varchar(255) NOT NULL,
	CONSTRAINT "users_email_unique" UNIQUE("email")
);

Pull your database schema:

npx drizzle-kit pull

The result of introspection will be a schema.ts file, meta folder with snapshots of your database schema, sql file with the migration and relations.ts file for relational queries.

Here is an example of the generated schema.ts file:

// table schema generated by introspection
import { pgTable, unique, integer, varchar } from "drizzle-orm/pg-core"
import { sql } from "drizzle-orm"

export const users = pgTable("users", {
	id: integer().primaryKey().generatedAlwaysAsIdentity({ name: "users_id_seq", startWith: 1, increment: 1, minValue: 1, maxValue: 2147483647, cache: 1 }),
	name: varchar({ length: 255 }).notNull(),
	age: integer().notNull(),
	email: varchar({ length: 255 }).notNull(),
}, (table) => [
	unique("users_email_unique").on(table.email)
]);

Learn more about introspection in the documentation.

Step 5 - Transfer code to your actual schema file

We recommend transferring the generated code from drizzle/schema.ts and drizzle/relations.ts to the actual schema file. In this guide we transferred code to src/db/schema.ts. Generated files for schema and relations can be deleted. This way you can manage your schema in a more structured way.

 ├ 📂 drizzle
 │ ├ 📂 meta
 │ ├ 📜 migration.sql
 │ ├ 📜 relations.ts ────────┐
 │ └ 📜 schema.ts ───────────┤
 ├ 📂 src                    │ 
 │ ├ 📂 db                   │
 │ │ ├ 📜 relations.ts <─────┤
 │ │ └ 📜 schema.ts <────────┘
 │ └ 📜 index.ts         
 └ …

Step 6 - Connect Drizzle ORM to the database

Create a index.ts file in the src/db directory and initialize the connection:

import { drizzle } from 'drizzle-orm/vercel-postgres';

const db = drizzle();

If you need to provide your existing driver:

import { sql } from '@vercel/postgres';
import { drizzle } from 'drizzle-orm/vercel-postgres';

const db = drizzle({ client: sql })

Step 7 - Query the database

import 'dotenv/config';
import { eq } from 'drizzle-orm';
import { drizzle } from 'drizzle-orm/vercel-postgres';
import { usersTable } from './db/schema';

async function main() {
  const db = drizzle();

  const user: typeof usersTable.$inferInsert = {
    name: 'John',
    age: 30,
    email: '[email protected]',
  };

  await db.insert(usersTable).values(user);
  console.log('New user created!')

  const users = await db.select().from(usersTable);
  console.log('Getting all users from the database: ', users)
  /*
  const users: {
    id: number;
    name: string;
    age: number;
    email: string;
  }[]
  */

  await db
    .update(usersTable)
    .set({
      age: 31,
    })
    .where(eq(usersTable.email, user.email));
  console.log('User info updated!')

  await db.delete(usersTable).where(eq(usersTable.email, user.email));
  console.log('User deleted!')
}

main();

Step 8 - Run index.ts file

To run any TypeScript files, you have several options, but let’s stick with one: using tsx

You’ve already installed tsx, so we can run our queries now

Run index.ts script

npm

yarn

pnpm

bun

npx tsx src/index.ts

yarn tsx src/index.ts

pnpm tsx src/index.ts

bun tsx src/index.ts

tips

We suggest using bun to run TypeScript files. With bun, such scripts can be executed without issues or additional settings, regardless of whether your project is configured with CommonJS (CJS), ECMAScript Modules (ESM), or any other module format. To run a script with bun, use the following command:

bun src/index.ts

If you don’t have bun installed, check the Bun installation docs

Step 9 - Update your table schema (optional)

If you want to update your table schema, you can do it in the schema.ts file. For example, let’s add a new column phone to the users_table:

import { pgTable, unique, integer, varchar } from "drizzle-orm/pg-core"
import { sql } from "drizzle-orm"

export const users = pgTable("users", {
	id: integer().primaryKey().generatedAlwaysAsIdentity({ name: "users_id_seq", startWith: 1, increment: 1, minValue: 1, maxValue: 2147483647, cache: 1 }),
	name: varchar({ length: 255 }).notNull(),
	age: integer().notNull(),
	email: varchar({ length: 255 }).notNull(),
  phone: varchar(),
}, (table) => [
	unique("users_email_unique").on(table.email)
]);

Step 10 - Applying changes to the database (optional)

You can directly apply changes to your database using the drizzle-kit push command. This is a convenient method for quickly testing new schema designs or modifications in a local development environment, allowing for rapid iterations without the need to manage migration files:

npx drizzle-kit push

Read more about the push command in documentation.

Tips

Alternatively, you can generate migrations using the drizzle-kit generate command and then apply them using the drizzle-kit migrate command:

Generate migrations:

npx drizzle-kit generate

Apply migrations:

npx drizzle-kit migrate

Read more about migration process in documentation.

Step 11 - Query the database with a new field (optional)

import 'dotenv/config';
import { eq } from 'drizzle-orm';
import { drizzle } from 'drizzle-orm/vercel-postgres';
import { usersTable } from './db/schema';

async function main() {
  const db = drizzle();

  const user: typeof usersTable.$inferInsert = {
    name: 'John',
    age: 30,
    email: '[email protected]',
    phone: '123-456-7890',
  };

  await db.insert(usersTable).values(user);
  console.log('New user created!')

  const users = await db.select().from(usersTable);
  console.log('Getting all users from the database: ', users)
  /*
  const users: {
    id: number;
    name: string;
    age: number;
    email: string;
    phone: string | null;
  }[]
  */

  await db
    .update(usersTable)
    .set({
      age: 31,
    })
    .where(eq(usersTable.email, user.email));
  console.log('User info updated!')

  await db.delete(usersTable).where(eq(usersTable.email, user.email));
  console.log('User deleted!')
}

main();