> ## Documentation Index
> Fetch the complete documentation index at: https://kb.hosting.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Connecting to PostgreSQL using Python

> Learn to connect to a PostgreSQL database using Python with concise code snippets, step-by-step guidance, and related resources.

This article describes how to connect to a PostgreSQL database using Python.

<Tip>
  The PostgreSQL databases and users must already exist before you can use these methods. For information about how to manage PostgreSQL databases using cPanel, please see [this article](/docs/managing-postgresql-databases).
</Tip>

## Connecting to PostgreSQL using Python

Before you can access PostgreSQL databases using Python, you must install one (or more) of the following packages in a virtual environment:

* *psycopg2*: This package contains the **psycopg2** module.

* *PyGreSQL*: This package contains the **pgdb** module.

Both of these packages support [Python's portable SQL database API](https://www.python.org/dev/peps/pep-0249/). This means that if you switch from one module to another, you can reuse almost all of your existing code (the code sample below demonstrates how to do this).

### Setting up the Python virtual environment and installing a PostgreSQL package

To set up the Python virtual environment and install a PostgreSQL package, follow these steps:

1. Log in to your account [using SSH](/docs/using-ssh-secure-shell).

2. At the command prompt, type the following command:

   ```bash theme={null}
   cd ~
   ```

3. To create a virtual environment, type one of the following commands:

   * If you are running Python **3.x**, type the following command:

     ```bash theme={null}
     python3 -m venv sqlenv
     ```

   * If you are running Python **2.x**, type the following command:

     ```bash theme={null}
     virtualenv sqlenv
     ```

   > 📘 Note
   >
   > Subsequent commands in this procedure assume that the environment is named *sqlenv*. You can use any environment name you want, but make sure you replace all occurrences of *sqlenv* with your own environment name.

4. To activate the virtual environment, type the following command:

   ```bash theme={null}
   source sqlenv/bin/activate
   ```

   > 📘 Note
   >
   > The command prompt now starts with **(sqlenv)** to indicate that you are working in a Python virtual environment. All of the following commands in this procedure assume that you are working within the virtual environment. If you log out of your SSH session (or deactivate the virtual environment by using the **deactivate** command), make sure you reactivate the virtual environment before following the steps below and running the sample code.

5. To update *pip* in the virtual environment, type the following command:

   ```bash theme={null}
   pip install -U pip
   ```

6. Type the command for the package you want to install:

   * To install the *psycopg2* package, type the following command:

     ```bash theme={null}
     pip install psycopg2
     ```

   * To install the *PyGreSQL* package, type the following command:

     ```bash theme={null}
     pip install pygresql
     ```

### Code sample using Python's portable SQL database API

After you install a PostgreSQL package in the virtual environment, you are ready to work with actual databases. The following sample Python code demonstrates how to do this, as well as just how easy it is to switch between the different SQL package implementations using the portable SQL database API. The sample code works with Python 2.7 and Python 3.x.

In your own code, replace ***username*** with the PostgreSQL database username, ***password*** with the database user's password, and ***dbname*** with the database name:

```python theme={null}
#!/usr/bin/python

from __future__ import print_function

hostname = 'localhost'
username = 'username'
password = 'password'
database = 'dbname'

## Simple routine to run a query on a database and print the results:
def doQuery( conn ):
    cur = conn.cursor()

    cur.execute( "SELECT fname, lname FROM employee" )

    for firstname, lastname in cur.fetchall():
        print( firstname, lastname )

print( "Using psycopg2:" )
import psycopg2
myConnection = psycopg2.connect( host=hostname, user=username, password=password, dbname=database )
doQuery( myConnection )
myConnection.close()

print( "Using PyGreSQL (pgdb):" )
import pgdb
myConnection = pgdb.connect( host=hostname, user=username, password=password, database=database )
doQuery( myConnection )
myConnection.close()
```

This example creates a series of **Connection** objects that opens the same database using different PostgreSQL modules. Because both of these modules use the portable SQL database API interface, they are able to use the code in the **doQuery()** function without any modifications.

When you have a **Connection** object associated with a database, you can create a **Cursor** object. The **Cursor** object enables you to run the **execute()** method, which in turn enables you to run raw SQL statements (in this case, a *SELECT* query on a table named *employee*).

<Note>
  As you can see, Python's portable SQL database API makes it very easy to switch between PostgreSQL modules in your code. In the sample above, the only code changes necessary to use a different module are to the **import** and **connect** statements.
</Note>

### Code sample using the legacy pg module

The *PyGreSQL* package also includes a legacy **pg** module that you can use to connect to PostgreSQL. Although it is easy to use, it does not implement Python's portable SQL database API.

The following code sample demonstrates how to use the **pg** module to connect to a PostgreSQL database. Replace ***username*** with the PostgreSQL database username, ***password*** with the database user's password, and ***dbname*** with the database name:

```python theme={null}
#!/usr/bin/python

from __future__ import print_function

import pg

conn = pg.DB( host="localhost", user="username", passwd="password", dbname="dbname" )

result = conn.query( "SELECT fname, lname FROM employee" )

for firstname, lastname in result.getresult():
    print( firstname, lastname )

conn.close()
```

This example creates a **Connection** object that opens the PostgreSQL database using the specified parameters. Once you have a **Connection** object associated with the database, you can query the database directly using raw SQL statements (in this case, a *SELECT* query on a table named *employee*). The **getresult()** method reads the result data returned by the query. Finally, the **close()** method closes the connection to the database.

## More information

* For more information about Python's portable SQL database API, please visit [https://www.python.org/dev/peps/pep-0249](https://www.python.org/dev/peps/pep-0249).

* For more information about the *psycopg2* package, please visit [https://pypi.python.org/pypi/psycopg2](https://pypi.python.org/pypi/psycopg2).

* For more information about the *PyGreSQL* package, please visit [https://pypi.python.org/pypi/PyGreSQL](https://pypi.python.org/pypi/PyGreSQL).

## Related articles

* [Using virtualenv and pip](/docs/using-virtualenv-and-pip)

* [Connecting to PostgreSQL using psql](/docs/connect-to-postgresql-from-the-command-line)

* [Connecting to PostgreSQL using PHP](/docs/connect-to-postgresql-using-php)