This guide introduces you to the installation and usage of the Python Connector for Polypheny. We’ll go through a series of examples illustrating common database operations such as user login, table creation, data manipulation, and data retrieval. Finally, we’ll unite these individual pieces into a coherent, comprehensive Python program.
The Python Connector for Polypheny is essential for running Python applications with Polypheny. This connector can be installed on Linux, macOS, and Windows operating systems. The complete developer notes, along with the source code, are available on GitHub.
Before installing the Python Connector, you need to ensure you have the right software packages:
The Python Connector requires Python 3.6 or later. To verify your Python version, execute the following command in your terminal:
The Python Connector is installed via pip, a popular Python package installer and manager. You should have pip version 19.0 or later. You can upgrade pip using the following command:
python -m pip install --upgrade pip
If you have both Python 2.7.x and Python 3.x installed, use pip3 to install the connector with Python 3.x. Also, we recommend creating a virtual environment using anaconda.
The Python Connector for Polypheny is available on PyPI. A detailed change log is also provided, so you can explore the updates in each release.
To install the connector, execute the following command, replacing
<version> with the specific version you want to install:
pip install polypheny==<version>
For the latest version, simply run:
pip install polypheny
After installation, verify the Python Connector by creating a Python file (e.g.,
validate.py) containing the following sample code. This script establishes a connection to Polypheny and retrieves some dummy information:
#!/usr/bin/env python import polypheny # Connect to Polypheny connection = polypheny.connect('<polypheny_host>', 20591, user='pa', password='') # Get a cursor cursor = connection.cursor() # Execute a query cursor.execute("SELECT * FROM emps") result = cursor.fetchall() print("Result Set: ", result) # Close the connection connection.close()
Before running this script, replace
<polypheny_host> with the DNS entry of your Polypheny installation (
localhost if installed locally) and update
password with your Polypheny credentials.
To run the file, execute the command:
If the connection is successful, you will see output similar to:
Result Set: [[100, 10, 'Bill', 10000, 1000], [110, 10, 'Theodore', 11500, 250], [150, 20, 'Sebastian', 7000, 400], [200, 30, 'Eric', 8000, 500]]
Congratulations! You’ve now connected your Python application to Polypheny. Now let’s dive into using the Python Connector to interact with Polypheny.
To interact with Polypheny from Python, we first import the
Then, we establish a connection to Polypheny. In the below example, we connect to a Polypheny instance running on the local machine (
localhost) on port 20591 using the user credentials for ‘pa’ with an empty password:
connection = polypheny.connect('localhost', 20591, user='pa', password='')
Once connected, we create a
cursor object from the connection to enable interaction with the database. This
cursor object serves as a mediator, facilitating both data read and write operations with Polypheny:
cursor = connection.cursor()
To retrieve data from a table in the database, we use the
execute method of the
cursor object, passing an SQL
SELECT statement as a string argument. The
fetchall method then retrieves all the records resulting from the executed query:
cursor.execute("SELECT * FROM emps") result = cursor.fetchall() print(result)
Writing data to Polypheny involves using an SQL
INSERT statement passed to the
execute method. The changes are then committed to the database with the
commit method of the
cursor.execute("INSERT INTO dummy VALUES (407 , 'de', 93)") connection.commit()
Upon completion of all necessary database operations, it’s best practice to close the
connection object. This operation automatically closes the associated
cursor object as well, freeing up resources:
The Polypheny Connector for Python incorporates the standard Python logging module to record its activity, aiding in tracing and debugging application behavior. The
basicConfig method of the
logging module sets up the most basic logging configuration:
import logging logging.basicConfig(format='%(levelname)s:%(message)s', level=logging.DEBUG)
Below is an integrative Python program that demonstrates the usage of the Python Connector for Polypheny, encompassing connection setup, table creation, data insertion, data retrieval, and connection termination:
import polypheny import logging # Setup logging logging.basicConfig(format='%(levelname)s:%(message)s', level=logging.DEBUG) # Connect to Polypheny connection = polypheny.connect('localhost', 20591, user='pa', password='') cursor = connection.cursor() # Create a new table cursor.execute("CREATE TABLE dummy (id INT NOT NULL, text VARCHAR(2), num INT, PRIMARY KEY(id))") # Insert data into the table cursor.execute("INSERT INTO dummy VALUES (407 , 'de', 93)") connection.commit() # Query data from the table cursor.execute("SELECT * from dummy") result = cursor.fetchall() print("Result Set: ", result) # Close the connection connection.close()
This code provides a great starting point for further exploration of the Python Connector and its capabilities within the context of Polypheny.