Country Python II

Question

Améliorer le programme Python ci-après  :

  • Intégrer une gestion d'exception pour la phase de connexion

  • Utiliser fetchall à la place de fetchone

  • Afficher - Île-de-France (d=999) à la place de Île-de-France 999

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#!/usr/bin/python3
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import psycopg2
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conn = psycopg2.connect("dbname='mydb' user='me' host='localhost' password='secret'")
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sql = "SELECT name, population/area AS density FROM region ORDER BY density DESC";
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resultat = conn.cursor()
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resultat.execute(sql)
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ligne = resultat.fetchone()
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while ligne:
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        name = ligne[0]
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        density = ligne[1]
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        print(name, density)
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        ligne = resultat.fetchone()
Solution
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#!/usr/bin/python3
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import psycopg2
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try:
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  conn = psycopg2.connect("dbname='mydb' user='me' host='localhost' password='secret'")
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except psycopg2.OperationalError as e:
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  print ("I am unable to connect to the database")
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  raise(e)
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sql = "SELECT name, population/area AS density FROM region ORDER BY density DESC";
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cur = conn.cursor()
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cur.execute(sql)
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res = cur.fetchall()
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for raw in res:
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        name = raw[0]
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        density = raw[1]
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        print ("- %s (d=%i)" % (name, density))