Différences

Ci-dessous, les différences entre deux révisions de la page.

--- tech:notes_postgres_python [2025/11/20 16:38] – Jean-Baptiste
+++ tech:notes_postgres_python [2026/06/07 19:12] (Version actuelle) – modification externe 127.0.0.1
@@ Ligne 1: / Ligne 1: @@
+<!DOCTYPE markdown>
+{{tag>Python SQL Postgres CA}}
+# Notes Postgres Python
+Voir :
+* http://www.postgresqltutorial.com/postgresql-python/transaction/
+* http://nessy.info/?p=886
+Voir aussi :
+* [[connexion_a_une_base_proprietaire_-_python_-_jdbc_-_odbc|Connexion à une base propriétaire - Python - JDBC - ODBC]]
+* pg8000
+* python-sqlalchemy
+## Exemple
+Vacuum
+~~~python
+dbname = 'dbname'
+user = 'postgres'
+host = '192.168.1.10'
+password = 'password'
+import psycopg2
+c = "dbname='%s' user='%s' host='%s' password='%s'"
+conn = psycopg2.connect(c % (dbname, user, host, password))
+conn.set_session(autocommit=True)
+cur=conn.cursor()
+cur.execute("VACUUM FULL ANALYSE")
+cur.close()
+conn.close()
+~~~
+Query select - Fetch
+~~~python
+cur=conn.cursor()
+cur.execute("SELECT plop.purge()")
+if cur.rowcount > 0:
+    row = cur.fetchone()
+else:
+    row = None
+while row is not None:
+    print(row)
+    row = cur.fetchone()
+cur.close()
+conn.commit()
+conn.close()
+~~~
+## with statement
+Source : https://www.psycopg.org/docs/usage.html#with-statement
+~~~python
+conn = psycopg2.connect(DSN)
+with conn:
+    with conn.cursor() as curs:
+        curs.execute(SQL1)
+with conn:
+    with conn.cursor() as curs:
+        curs.execute(SQL2)
+conn.close()
+~~~
+### Warning
+Unlike file objects or other resources, exiting the connection’s with block doesn’t close the connection, but only the transaction associated to it. If you want to make sure the connection is closed after a certain point, you should still use a try-catch block :
+~~~python
+conn = psycopg2.connect(DSN)
+try:
+    # connection usage
+finally:
+    conn.close()
+~~~