// callback
client.query('SELECT NOW() as now', (err, res) => {
if (err) {
console.log(err.stack)
} else {
console.log(res.rows[0])
}
})
// promise
client
.query('SELECT NOW() as now')
.then(res => console.log(res.rows[0]))
.catch(e => console.error(e.stack))