# Connect from psql, Python and Node.js

> Stolon speaks the PostgreSQL wire protocol, so psql, psycopg, psycopg2, SQLAlchemy, node-postgres and postgres.js connect unchanged. The database name in the connection string selects the branch.

Source: https://stolondb.com/guides/connect/ · Page title: Connect to Stolon from psql, Python and Node.js

Your Postgres driver connects unchanged. **The database name selects the branch.**

## The connection string

Copy it from your database's **Connect** page. The database name is `<database>.<branch>`:

```text
postgresql://app:<password>@db.stolondb.com/acme.main
```

## psql

```sh
psql "postgresql://app:<password>@db.stolondb.com/acme.main"
```

```sql
CREATE TABLE accounts (id int PRIMARY KEY, owner text NOT NULL, balance numeric(10,2) NOT NULL);
INSERT INTO accounts VALUES (1, 'ada', 100.00), (2, 'lin', 250.00), (3, 'sam', 75.50);
CREATE DATABASE scratch;          -- a branch of main: the whole database, copied by reference
\c acme.scratch
UPDATE accounts SET balance = 0;  -- main does not see this
\l
```

## Python with psycopg 3

```python
import psycopg

# CREATE DATABASE cannot run inside a transaction block, as in Postgres,
# so open the connection that makes a branch with autocommit.
with psycopg.connect("postgresql://app:<password>@db.stolondb.com/acme.main", autocommit=True) as conn:
    print(conn.execute("SELECT id, owner, balance FROM accounts ORDER BY id").fetchall())
    conn.execute("CREATE DATABASE py_branch")

with psycopg.connect("postgresql://app:<password>@db.stolondb.com/acme.py_branch") as conn:
    conn.execute("UPDATE accounts SET balance = balance * 2")
    print(conn.execute("SELECT sum(balance) FROM accounts").fetchone())
```

## Python with psycopg2 and SQLAlchemy

```python
import psycopg2

conn = psycopg2.connect(host="db.stolondb.com", user="app", password="<password>", dbname="acme.main")
cur = conn.cursor()
cur.execute("SELECT count(*), sum(balance) FROM accounts")
print(cur.fetchone())
conn.close()
```

```python
from sqlalchemy import create_engine, text

engine = create_engine("postgresql+psycopg2://app:<password>@db.stolondb.com/acme.py_branch")
with engine.connect() as conn:
    print(conn.execute(text("SELECT sum(balance) FROM accounts")).scalar())
```

## Node.js with node-postgres

```js
import pg from "pg";

const main = new pg.Client("postgresql://app:<password>@db.stolondb.com/acme.main");
await main.connect();
console.log((await main.query("SELECT id, owner, balance FROM accounts ORDER BY id")).rows);
await main.query("CREATE DATABASE node_branch");
await main.end();

const branch = new pg.Client("postgresql://app:<password>@db.stolondb.com/acme.node_branch");
await branch.connect();
await branch.query("UPDATE accounts SET balance = $1 WHERE id = $2", [0, 1]);
console.log((await branch.query("SELECT balance FROM accounts WHERE id = 1")).rows);
await branch.end();
```

## Node.js with postgres.js

```js
import postgres from "postgres";

const sql = postgres("postgresql://app:<password>@db.stolondb.com/acme.node_branch");
console.log(await sql`SELECT id, balance FROM accounts WHERE id = ${1}`);
await sql.end();
```

## Tips

- Run `CREATE DATABASE` with autocommit, as with Postgres.
- Quote names that are not plain identifiers: `CREATE DATABASE "agent-7"`.
- Check your own queries with [Will it run?](https://stolondb.com/compatibility/)