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
Functions
The FIRST and LAST functions in Oracle SQL
This is the written version of a lesson from my SQL Course, in which I show how to use the FIRST and LAST functions. Like some other functions you probably know, these functions can be used either as aggregate functions… Continue Reading
OTN Appreciation Day : The Power of Oracle SQL
I’m writing this post as a contribution to the OTN appreciation day because I think Tim Hall’s idea was awesome. If I have to choose the feature I like and enjoy the most, it has to be the power of… 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
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
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
Adding optional conditions to your queries
The NVL function is very useful in a lot of different situations and is probably one of the most widely used among Oracle developers. One of the ways we can use it is to write queries that have ‘optional’ conditions.… Continue Reading
Oracle NVL, NVL2 and COALESCE functions
I have seen quite a few questions on internet forums and knowledge exchange sites about Oracle NVL, NVL2 and COALESCE functions for handling nulls, so I decided to write an article about them today. Those functions are actually similar, but… Continue Reading