The SQL Group By Clause
This is the written version of a lesson from my SQL Course, in which I introduce students to the awesome and very commonly used SQL GROUP BY clause. If you want to follow along, here is the script you can… Continue Reading
SQL
The FIRST and LAST functions in Oracle SQL
This is the written version of a lesson from The Ultimate Oracle SQL Course, in which I show how to use the Oracle FIRST and LAST functions. Like some other functions you probably know, these functions can be used either… Continue Reading
Pairwise Comparisons With Subqueries in Oracle SQL
I recently received a question about Pairwise Subqueries from one of the students in my SQL course, and I thought it would be a good idea to make my answer a blog post, since I did a couple of Google… Continue Reading
Prioritizing Rows: The Ranking Functions
Ranking functions are some of the most commonly used analytic functions, and although the “ranking” category can quickly make you think about Top-N queries, that is actually not the only type of problems you can solve with them. In this… Continue Reading
The awesome Pivot and Unpivot Features in Oracle SQL
I decided to write about the Pivot and Unpivot clauses, because I find them very useful and powerful. In this article I will try to explain how they are used and show you some examples of the things you can… Continue Reading
Understanding Analytic Functions
Analytic functions in Oracle SQL are very useful and are utilized by many people, but sometimes without completely understanding how they work or what data they operate on. This article does not focus on a specific function, but on analytic… Continue Reading
Top-N queries in Oracle SQL
I decided to write about Top-N queries today because even though there are lots of articles and documentation about the correct way to do it in Oracle out there, I have seen this question asked on different forums, and to… Continue Reading
The WITH clause to the rescue!
This time I’m just writing to tell you a story about the WITH clause, because it is really powerful and vastly underutilized. You can read the basics about the WITH clause in my previous article about subqueries. So, this is… Continue Reading
Oracle Inner Join Syntax : 4 different ways
I’ve worked with Oracle databases for many years, and during this time I have seen code written by lots of different people. One thing I have noticed is that with few exceptions, people who started working with Oracle many years… Continue Reading
The Powerful DECODE Function
Oracle’s DECODE is one of the functions I find more powerful and one that over the years I have used thousands of times to solve several different kinds of problems. Here I’m going to talk a little bit about how… Continue Reading