How to Query Data from a Database Using SQL Conditions in Python

Learn how to efficiently fetch and format data from your SQLite database using Python. Discover tips on how to structure your outputs for better readability.
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This video is based on the question https://stackoverflow.com/q/65511501/ asked by the user 'Kristler' ( https://stackoverflow.com/u/14111848/ ) and on the answer https://stackoverflow.com/a/65514140/ provided by the user 'limserhane' ( https://stackoverflow.com/u/14913991/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

Working with databases can sometimes feel overwhelming, especially when trying to retrieve and display data in a readable format. If you're using Python with SQLite and have encountered a situation where you want to query data based on specific conditions, this guide is for you. We will look into common problems faced when querying data and how to format the output for clear visibility.

In this post, we will address a typical problem: retrieving both column names and corresponding data from an employee database. By the end, you'll have a better understanding of how to format your data output to be more user-friendly.

The Problem

You are tasked with retrieving employee details, including names, surnames, hire dates, phone numbers, emails, addresses, positions, and badge IDs from a SQLite database using Python. However, upon fetching the data, your output ends up looking messy, displaying tuples instead of clearly formatted names and details. Here's the output you currently get:

[[See Video to Reveal this Text or Code Snippet]]

Instead, you'd prefer it to be displayed like this:

[[See Video to Reveal this Text or Code Snippet]]

Understanding the Existing Code

You have a function show_employee_id(ide) that retrieves data from the database. Here’s a simplified look at your function:

[[See Video to Reveal this Text or Code Snippet]]

In this function:

You're querying employee data based on the provided ID.

You're collecting the column names from the query's results.

The Solution

To get the output in your desired format, consider the following steps:

1. Fetch Data Efficiently

Instead of redundantly looping through the fetched data, directly utilize the fetchall() method within your output loop. Here’s how to do that effectively:

[[See Video to Reveal this Text or Code Snippet]]

2. How This Works

Zipping Columns with Data: By using zip(columns, row), each column name pairs with the respective value fetched in row. This makes it easy to format your output precisely as you need.

Formatted Strings: Using f-strings (formatted string literals), we effectively construct the output in a clean and readable manner.

3. Full Code Example

Here is the refined overall implementation you can use:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By restructuring the way you are outputting data from your SQLite queries in Python, you can enhance readability significantly. Instead of getting tuples as output, clear and concise formatting allows you to better understand and present the information you are working with.

Next time you need to query data and display it, remember these tips to streamline your code and enhance the user experience!