This article focus on connecting to a PostgreSQL database from Python.
Installation:
- Install PostgreSQL, If you haven’t installed it.
- We need to install the psycopg2 library to connect to a PostgreSQL database. Open the command prompt and run the below command to install psycopg2
pip3 install psycopg2
Creating a Database
You can create a Database in 2 Ways:
- Using pgAdmin 4 UI
- Using command
1. Using pgAdmin 4 UI
Go to pgAdmin and Follow these Steps.
- Local_server[Right Click] -> Create -> Database
Create Database from side menu pop-up
- Next, Fill out the form Database: WorkSpace and Save.
2. Create Database Using SQL query
Go to pgAdmin and follow these Steps:
Run the below Command in the Query tab
CREATE DATABASE WorkSpace;
Run the create database command
Connecting to the database
We need to connect to a PostgreSQL database using psycopg2.connect() function.
Where the attributes of connect() function are:
host = hostname, dbname = databaseName, user = username, password = [Your Password], port = [port_id]
In case you don’t know any of these connect() function attributes, you can follow the below steps:
Now You Know All the properties of this Database. Let’s continue.
Now, to connect to the database, we need to pass the attributes as arguments to the connect() function.
Syntax:
conn = psycopg2.connect(
host = 'localhost',
dbname = 'For_Practice',
user = 'postgres',
password = '[Password]',
port = 5432
)
Create a cursor:
- Create a cursor(i.e., curr) object and call its execute() method to execute queries.
- Where execute() method is used to run a query that is passed as a string.
Syntax:
cur = conn.cursor()
cur.execute('[SQL queries]')
In the end, We need to save the changes using commit() method and finally close the opened connection using close() method.
Syntax:
conn.commit() cur.close()
Python3
import psycopg2 conn = Nonetry: # connect to the PostgreSQL server print('Connecting to the PostgreSQL database...') conn = psycopg2.connect( host = 'localhost', dbname = 'For_Practice', user = 'postgres', password = '321654', port = 5432 ) # Creating a cursor with name cur. cur = conn.cursor() print('Connected to the PostgreSQL database') # Execute a query: # To display the PostgreSQL # database server version cur.execute('SELECT version()') print(cur.fetchone()) # Close the connection cur.close() except(Exception, psycopg2.DatabaseError) as error: print(error) finally: if conn is not None: conn.close() print('Database connection closed.') |
Output:
