Connection from python to postgresql

Question

I'm trying to do a connection to PostgreSQL 9.6 from Python 3.6 with Pycharm 2018.1.4 on Windows 10 with the connector psycopg2 in the version 2.7.5. I have the following code:

import os, psycopg2, psycopg2.extras
conexion = psycopg2.connect("dbname=Seguritec_BD user=SU host=localhost password=root port=5432")
psycopg2.OperationalError
cursor = conexion.cursor()
cursor.execute("Select * from Ejecutivos")
filas = cursor.fetchall()

It throws the next error:

Traceback (most recent call last):
  File "D:/Documentos/Proyectos Pycharm/Graficos Drones/Login.py", line 3, in <module>
    conexion = psycopg2.connect("dbname=Seguritec_BD user=SU host=localhost password=root port=5432")
  File "D:\Documentos\Proyectos Python 3.5\lib\site-packages\psycopg2\__init__.py", line 130, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
psycopg2.OperationalError

It's an empty OperationalError, there's no description of the error.

Can you help me to understand and fix this error, please?

Thanks, i changed the language, i hope it is undestandable. Thank you. — Uriel Mendoza, Aug 16 '18 at 22:07
Did you create the database Seguritec_BD on PostgreSQL? Did you start the postgres server? — hygorxaraujo, Aug 16 '18 at 22:08
Yes, it is much clearer now, thank you for translating your question :) Welcome to Stack Overflow. — Andras Deak -- Слава Україні, Aug 16 '18 at 22:14
Thank you a lot Andras!. @hygorxaraujo Yes, the BD has been created, but about the postgres server How can I make sure of that? — Uriel Mendoza, Aug 16 '18 at 22:16
Open a terminal (cmd or powershell) and type `net status postgresql-9.6` and check the output to see if it is running. I normally use linux so I'm not sure that will work, check this other SO question https://stackoverflow.com/q/36629963/2550932. — hygorxaraujo, Aug 16 '18 at 22:27
Thank you for that, i checked that answer. I was testing, and the server is started. — Uriel Mendoza, Aug 16 '18 at 22:41
What about your user (SU), does it really exist? Is the password correct? Does it have permission to access your database? I could get an error similar to yours giving the wrong credentials on connect. — hygorxaraujo, Aug 16 '18 at 22:49
Was there no message after `psycopg2.OperationalError`? Because when I tried to connect with the wrong information (user, password, database) I got something like `psycopg2.OperationalError: FATAL: database "learning" does not exist` — hygorxaraujo, Aug 16 '18 at 22:53

Maryan · Answer 1 · 2022-06-25T09:25:01.180

0

Test on Windows 10, PostgreSQL 14, Python 3.10.0, psycopg2 2.9.3

psycopg2.OperationalError same for wrong (user, password, database, privileges)

try to connect with to see verbose message

edited Jun 25 '22 at 09:25

answered Jun 25 '22 at 08:30

Maryan

71
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score -1 · Answer 2 · answered Aug 17 '18 at 00:55

You have an issue so simplify it by first only using Postgresql to confirm your connection, first try psql only, substituting your values into the connection string

psql -U postgres -d postgres -c "SELECT *  FROM pg_user;"

If you need reference

psql --help

Connection from python to postgresql

2 Answers2