Book Image

The Data Wrangling Workshop - Second Edition

By : Brian Lipp, Shubhadeep Roychowdhury, Dr. Tirthajyoti Sarkar
Book Image

The Data Wrangling Workshop - Second Edition

By: Brian Lipp, Shubhadeep Roychowdhury, Dr. Tirthajyoti Sarkar

Overview of this book

While a huge amount of data is readily available to us, it is not useful in its raw form. For data to be meaningful, it must be curated and refined. If you’re a beginner, then The Data Wrangling Workshop will help to break down the process for you. You’ll start with the basics and build your knowledge, progressing from the core aspects behind data wrangling, to using the most popular tools and techniques. This book starts by showing you how to work with data structures using Python. Through examples and activities, you’ll understand why you should stay away from traditional methods of data cleaning used in other languages and take advantage of the specialized pre-built routines in Python. Later, you’ll learn how to use the same Python backend to extract and transform data from an array of sources, including the internet, large database vaults, and Excel financial tables. To help you prepare for more challenging scenarios, the book teaches you how to handle missing or incorrect data, and reformat it based on the requirements from your downstream analytics tool. By the end of this book, you will have developed a solid understanding of how to perform data wrangling with Python, and learned several techniques and best practices to extract, clean, transform, and format your data efficiently, from a diverse array of sources.
Table of Contents (11 chapters)

8. RDBMS and SQL

Activity 8.01: Retrieving Data Accurately from Databases


These are the steps to complete this activity:

  1. Connect to the supplied petsdb database:
    import sqlite3
    conn = sqlite3.connect("petsdb")
  2. Write a function to check whether the connection has been successful:
    # a tiny function to make sure the connection is successful
    def is_opened(conn):
            conn.execute("SELECT * FROM persons LIMIT 1")
            return True
        except sqlite3.ProgrammingError as e:
            print("Connection closed {}".format(e))
            return False

    The output is as follows:

  3. Close the connection:
  4. Check whether the connection is open or closed:

    The output is as follows...