Skip to main content

Connect to Postgres

Edit on Github

Using the npm Postgres client, you can connect to a Postgres database running anywhere. Connection settings belong in environment variables rather than in the source, so the same code runs against your local database and production.

Import the Postgres package from npm
import postgres from "npm:postgres";
Read the connection settings from the standard libpq environment variables. Locally you might set PGDATABASE=test and nothing else; in production a managed database provides all of them. A common pattern is to keep these in a .env file and load it with the --env-file flag, for example: deno run --env-file -N -E main.ts
const sql = postgres({
  host: Deno.env.get("PGHOST") ?? "localhost",
  port: Number(Deno.env.get("PGPORT") ?? 5432),
  user: Deno.env.get("PGUSER") ?? "postgres",
  password: Deno.env.get("PGPASSWORD"),
  database: Deno.env.get("PGDATABASE") ?? "postgres",
});
Execute a SQL query. Connections open lazily on first use, so this is the first place a bad address or password surfaces; handle it instead of leaking a stack trace, and close the connection pool either way. Connection failures arrive as an AggregateError with the cause on its code property, for example ECONNREFUSED when nothing is listening.
try {
  const people = await sql`
    SELECT id, name FROM people
  `;
  console.log(people);
} catch (error) {
  const reason = (error as { code?: string }).code ?? String(error);
  console.error("Query failed:", reason); // Query failed: ECONNREFUSED
} finally {
Close the connection to the database
  await sql.end();
}

Run this example locally using the Deno CLI:

deno run -N -E https://docs.deno.com/examples/scripts/postgres.ts

Additional resources

Did you find what you needed?

Privacy policy