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By Kevin McAleer, 4 Minutes
In Module 2, we will cover the initial steps to set up Python and SQLite3, establish a connection to a database, and perform basic operations using Python’s sqlite3 module.
sqlite3
Before we start working with SQLite databases in Python, we need to ensure that Python and the sqlite3 module are installed on our system.
If Python is not already installed, you can download and install it from the official Python website (https://www.python.org). Choose the appropriate version for your operating system and follow the installation instructions.
Python’s sqlite3 module comes pre-installed with Python, so you don’t need to install any additional packages.
To work with a SQLite database in Python, we first need to establish a connection to the database. The sqlite3 module provides the necessary functions and methods to connect to a database file.
In Python, we use the sqlite3.connect() function to establish a connection to a SQLite database. We pass the path to the database file as an argument.
sqlite3.connect()
import sqlite3 # Connect to a database connection = sqlite3.connect('mydatabase.db')
This code creates a connection to a database file named mydatabase.db. If the file doesn’t exist, SQLite will create a new database file at that location.
mydatabase.db
After we finish working with the database, it’s important to close the connection to release system resources. We can do this by calling the close() method on the connection object.
close()
connection.close()
By closing the connection, we ensure that any changes made to the database are properly saved.
Once we establish a connection to the database, we can execute SQL statements using the connection object.
To create a table in a SQLite database, we use the execute() method and provide a SQL CREATE TABLE statement as a string.
execute()
CREATE TABLE
# Create a table connection.execute(''' CREATE TABLE books ( id INTEGER PRIMARY KEY, title TEXT, author TEXT, year INTEGER ) ''')
In this example, we create a table named books with columns for id, title, author, and year. The id column is defined as the primary key.
books
id
title
author
year
To insert data into a table, we use the execute() method with an SQL INSERT statement.
INSERT
# Insert data into the table connection.execute("INSERT INTO books (title, author, year) VALUES (?, ?, ?)", ("The Great Gatsby", "F. Scott Fitzgerald", 1925))
In this example, we insert a record into the books table, providing values for the title, author, and year columns.
To retrieve data from a table, we use the execute() method with an SQL SELECT statement. We then fetch the results using the fetchall() method.
SELECT
fetchall()
# Query data from the table result = connection.execute("SELECT * FROM books") data = result.fetchall() # Process the retrieved data for row in data: print(row)
This code retrieves all records from the books table and prints each row of data.
When working with databases, it’s essential to handle potential errors and exceptions gracefully. Python’s try and except statements can be used to catch and handle exceptions raised during database operations.
try
except
try: # Database operations connection.execute("...") # ... except sqlite3.Error as e: # Handle the exception print(f"An error occurred: {e}")
By incorporating exception handling, we can provide informative error messages and take appropriate actions in case of any issues.
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