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The FIRST and LAST functions in Oracle SQL

Posted on September 27, 2018 by Carlos

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 →

Functions, SQL aggregate, analytic, FIRST, function, functions, LAST, Oracle, SQL
2

Pairwise Comparisons With Subqueries in Oracle SQL

Posted on September 11, 2018 by Carlos

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 →

SQL Oracle, SQL, Subquery
20

How to Change Oracle SQL Developer Language

Posted on April 18, 2018 by Carlos

*Originaly published on August 8th 2015.   Today I installed SQL developer on a machine whose operating system is Windows 8 in Spanish, and SQL Developer got installed in Spanish too :-/ Even though Spanish is my first language, I… Continue Reading →

SQL Developer English, language, Oracle, SQL Developer, user interface
30

Count(*) Vs Count(1) Again?

Posted on January 31, 2017 by Carlos

I decided to write this article because the question keeps being asked, and I usually find myself explaining my answer again and again and/or looking for links to someone else’s articles that can help support my answer. Here  I discuss… Continue Reading →

SQL, Tuning 10053, count, COUNT(1), optimizer, query, Trace, Transformation
0

OTN Appreciation Day : The Power of Oracle SQL

Posted on October 11, 2016 by Carlos

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 →

Functions, SQL features, OTN
4

Prioritizing Rows With The Ranking Functions

Posted on August 25, 2016 by Carlos

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 →

Functions, SQL analytic, function, functions, Oracle, prioritize, ranking, SQL, top-n
9

The awesome Pivot and Unpivot Features in Oracle SQL

Posted on June 10, 2016 by Carlos

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 →

SQL columns, convert, Oracle, pivot, rotate, rows, SQL, transpose, unpivot
11

Understanding Analytic Functions

Posted on April 17, 2016 by Carlos
analytic functions windowing clause

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 →

Functions, SQL analytic, function, functions, Oracle, partition, SQL, window, windowing
23

Understanding a Query’s Execution Plan

Posted on January 30, 2016 by Carlos

One of the most basic tasks you need to perform when tuning SQL statements is determining the causes of the performance problem, and to do that, you will most likely need to analyze the execution plan of the problematic statement.… Continue Reading →

SQL, SQL Developer, Tuning access path, autotrace, cost, execution plan, explain plan, Join, optimizer, SQL Developer, tuning
10

Top-N queries in Oracle SQL

Posted on November 24, 2015 by Carlos

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 →

SQL dense_rank, pseudocolumn, rank, row_number, rownum, SQL, top-n

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  • The FIRST and LAST functions in Oracle SQL
  • Pairwise Comparisons With Subqueries in Oracle SQL
  • How to Change Oracle SQL Developer Language
  • Count(*) Vs Count(1) Again?
  • OTN Appreciation Day : The Power of Oracle SQL

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