Run an application transaction

A transaction belongs to one connection. Check out one client and use it for every statement:

const client = await pool.connect()

try {
  await client.query('BEGIN')

  const note = await client.query(
    'INSERT INTO app.notes (title) VALUES ($1) RETURNING id',
    ['Plan the week']
  )

  await client.query(
    'INSERT INTO app.note_tags (note_id, tag_id) VALUES ($1, $2)',
    [note.rows[0].id, 1]
  )

  await client.query('COMMIT')
} catch (error) {
  await client.query('ROLLBACK')
  throw error
} finally {
  client.release()
}

Do not call pool.query() inside this transaction. The pool may choose another connection.