How to use Planetscale with Deno

Planetscale is a MySQL-compatible serverless database that is designed with a developer workflow where developers can create, branch, and deploy databases from the command line.

View source here.

We'll use the Planetscale serverless driver, @planetscale/database, to work with Deno. First we want to create main.ts and import the connect method from this package:

import { connect } from "npm:@planetscale/database@^1.4";

Configuring our connection Jump to heading#

The connection requires three credentials: host, username, and password. These are database-specific, so we first need to create a database in Planetscale. You can do that by following the initial instructions here. Don't worry about adding the schema—we can do that through @planetscale/database.

Once you have created the database, head to Overview, click "Connect", and choose "Connect with @planetscale/database" to get the host and username. Then click through to Passwords to create a new password for your database. Once you have all three you can plug them in directly, or better, store them as environment variables:

export HOST=<host>
export USERNAME=<username>
export PASSWORD=<password>

Then call them using Deno.env:

const config = {
  host: Deno.env.get("HOST"),
  username: Deno.env.get("USERNAME"),
  password: Deno.env.get("PASSWORD"),
};

const conn = connect(config);

This will also work on Deno Deploy if you set the environment variables in the dashboard. Run with:

deno run --allow-net --allow-env main.ts

The conn object is now an open connection to our Planetscale database.

Creating and populating our database table Jump to heading#

Now that you have the connection running, you can conn.execute() with SQL commands to create tables and insert the initial data:

await conn.execute(
  "CREATE TABLE dinosaurs (id int NOT NULL AUTO_INCREMENT PRIMARY KEY, name varchar(255) NOT NULL, description varchar(255) NOT NULL);",
);
await conn.execute(
  "INSERT INTO `dinosaurs` (id, name, description) VALUES (1, 'Aardonyx', 'An early stage in the evolution of sauropods.'), (2, 'Abelisaurus', 'Abels lizard has been reconstructed from a single skull.'), (3, 'Deno', 'The fastest dinosaur that ever lived.')",
);

Querying Planetscale Jump to heading#

We can use same conn.execute() to also write our queries. Let's get a list of all our dinosaurs:

const results = await conn.execute("SELECT * FROM `dinosaurs`");
console.log(results.rows);

The result:

[
  {
    id: 1,
    name: "Aardonyx",
    description: "An early stage in the evolution of sauropods.",
  },
  {
    id: 2,
    name: "Abelisaurus",
    description: "Abels lizard has been reconstructed from a single skull.",
  },
  { id: 3, name: "Deno", description: "The fastest dinosaur that ever lived." },
];

We can also get just a single row from the database by specifying a dinosaur name:

const result = await conn.execute(
  "SELECT * FROM `dinosaurs` WHERE `name` = 'Deno'",
);
console.log(result.rows);

Which gives us a single row result:

[{ id: 3, name: "Deno", description: "The fastest dinosaur that ever lived." }];

You can find out more about working with Planetscale in their docs.