Sources:

• https://pynative.com/python-postgresql-tutorial/
• https://pynative.com/python-postgresql-select-data-from-table/

Si pip3 (l'installateur de modules de Python 3) n'est pas installé :

sudo apt install python3-pip

Ensuite installer Psycopg2 :

sudo pip3 install psycopg2

import getpass, psycopg2
 
username = "postgres"
password = None
conn     = None
 
def connect():
    global conn
 
    try:
        conn = psycopg2.connect(
            user     = username,
            password = password,
            host     = "localhost",
            port     = "5432",
            database = "my_database")
 
    except(Exception, psycopg2.Error) as error:
        conn = None
        print("Error while connecting:", error)
 
def disconnect():
    global conn
 
    if conn:
        conn.close
        print("Connection is closed")
 
password = getpass.getpass("Password for user %s :" % username)
try:
    connect()
    if conn:
        print("Connection OK")
finally:
    disconnect()

Renvoie un objet list dont chaque élément est un tuple :

cursor = conn.cursor()
try:
    cursor.execute("""
        select id, name, price
        from products
        where id >= %s
        order by id;
        """, (id,))
 
    rows = cursor.fetchall()
    print(type(rows))
 
    for row in rows:
        print(type(row))
        print(row)
 
finally:
    cursor.close()

Exemple de résultat :

<class 'list'>
<class 'tuple'>
(5, 'Bananes', Decimal('3.76'))
<class 'tuple'>
(6, 'Oranges', Decimal('6.20'))