Showing posts with label ORDER BY. Show all posts
Showing posts with label ORDER BY. Show all posts

Friday, 30 May 2025

LIMIT and OFFSET in PostgreSQL Queries || Queries in PostgreSQL || Postg...


Welcome to Lesson #40 in our PostgreSQL Full Playlist! In this video, we explore the powerful LIMIT and OFFSET clauses in PostgreSQL and how they help control the number of rows returned from a query. Whether you're building a backend for a web app or optimizing your data reports, mastering these clauses is essential.

We begin by understanding the syntax of LIMIT and OFFSET, followed by real-world examples using an employees table. You’ll learn how to:

  • Return a specific number of rows

  • Skip rows using OFFSET

  • Combine both for pagination

  • Use ORDER BY to ensure consistent and predictable results

We’ll also walk through advanced techniques like using CTEs (Common Table Expressions) for more powerful and flexible pagination with ROW_NUMBER().

🔍 Performance Alert: Learn why high OFFSET values can hurt performance and how to implement keyset pagination for large datasets.

Perfect for students, backend developers, and data analysts who want clean, performant SQL!

📌 Chapters:
0:00 - Introduction
1:10 - What is LIMIT and OFFSET?
2:45 - Creating the Employees Table
4:20 - LIMIT Examples
6:00 - OFFSET Examples
7:00 - Pagination with LIMIT & OFFSET
8:00 - Real-World Pagination Scenario
9:20 - Performance Notes & Keyset Pagination
11:00 - Using CTEs with ROW_NUMBER
12:30 - Conclusion

💡 Subscribe and turn on notifications so you don’t miss the next video: VALUES Lists in PostgreSQL!

Wednesday, 28 May 2025

ORDER BY in PostgreSQL Queries || Sorting Rows in PostgreSQL || PostgreS...



Welcome to video #39 in our PostgreSQL Full Playlist! 🎬 In this tutorial, we dive deep into one of the most essential clauses in SQL: the ORDER BY clause.

You'll learn how to sort query results in PostgreSQL based on one or more columns, expressions, and aliases. We also explain how to handle NULL values using NULLS FIRST and NULLS LAST, sort using column positions, and apply ORDER BY in advanced cases such as UNION, CTEs, and window functions.

Whether you're preparing for interviews, writing production queries, or optimizing reports and dashboards, understanding ORDER BY is critical for clear and consistent output.

We demonstrate everything with real examples and walkthroughs, using a practical employees table. This lesson also includes tips on performance, index use, and sorting text data with collation.

🎯 Topics Covered:

  • Basic ascending and descending sorting

  • Sorting by expressions like salary + bonus

  • Handling NULLs explicitly

  • Using column aliases and positions in ORDER BY

  • ORDER BY with UNION, DISTINCT, and LIMIT/OFFSET

  • Sorting randomly with RANDOM()

  • Analytical queries using RANK() with OVER

  • Performance tips using EXPLAIN

Make sure to subscribe and check out the full PostgreSQL series for complete mastery! 🚀

📌 Stay tuned for the next episode: LIMIT and OFFSET in PostgreSQL Queries