10 Feb 2021 Tihomir Babic Want to Learn Advanced PostgreSQL? Try This! Why and how should you learn advanced PostgreSQL? I’ll give you some tips that will help you achieve your goals. Keeping up with technology is hard; anyone who has foolishly tried to do so can confirm this (me, for example!). Most of the time, it just doesn't work. And to be brutally honest, keeping up with all the technologies all the time is pointless. You shouldn’t know everything about everything; it’s better to know as much as you need within the technology you use or want to use. Read more 1 Jan 2021 Tihomir Babic SQL JOIN Tips for Beginners If you’re a beginner and want to know how to start using SQL JOINs in your queries, you’ve come to the right place. Using the SQL JOIN clause is necessary if you want to query multiple tables. Sooner or later, you’ll have to use more than one table in a query. It’s the nature of relational databases in general – they consist of data that’s usually saved in multiple tables; in turn, these form a database. Read more 15 Dec 2020 Tihomir Babic How to Use CASE WHEN With SUM() in SQL This article will teach you what a CASE WHEN expression is in SQL and how to use it with a SUM() function and a GROUP BY statement. The examples are included to bolster your understanding. The best way to learn about CASE WHEN and how to use it with SUM() is our hands-on course Creating Basic SQL Reports. It contains over 90 interactive exercises that will teach you different techniques how to create complex reports in SQL. Read more 25 Nov 2020 Tihomir Babic How to Find All Employees Under Each Manager in SQL Have you ever been tasked with building an organizational chart – i.e. finding the employees under each manager in a company? In SQL, you can do that easier than you think! This article will show you how to get the answer using a recursive query. In the business world, it’s a very common task to list all the subordinate employees for a given manager. Is doing this hard enough to warrant a whole article? Read more 29 Oct 2020 Tihomir Babic What is the Difference Between COUNT(*), COUNT(1), COUNT(column), and COUNT(DISTINCT)? Have you noticed there are different variations of the SQL COUNT() function? This article explains the various arguments and their uses. As a SQL user, you’re probably quite familiar with the COUNT() function. Even though it’s relatively simple, it can be used in several different ways. Each way has a very different use. I imagine you’ve seen code that contains the function COUNT(*) or COUNT(1). You’ve probably also seen some other uses of the COUNT() function, such as COUNT(column name) and COUNT(DISTINCT column name), even if you haven’t used them. Read more 28 Oct 2020 Tihomir Babic What are SQL CTE Best Practices? Are you wondering what the best practices for using common table expressions are? This article will help you learn when to use a CTE and how to write it. If you have heard about SQL CTEs, you have probably noticed they’re often mentioned together with subqueries. Sometimes, people think there’s no difference compared to the subqueries, and there’s often debate about whether a CTE or subquery should be used to get a particular result. Read more 29 Sep 2020 Tihomir Babic Six Window Function Templates to Save in Your Code Editor Do you use window functions often enough to know them well but not often enough to remember all the details? Here are six window function codes you should save as templates. Window functions are a handy SQL option, but it doesn’t mean you use them all the time. Maybe you only use them occasionally; if that’s the case, you probably find yourself needing to refresh your memory every time you use them. Read more 17 Sep 2020 Tihomir Babic How to Use 2 CTEs in a Single SQL Query Have you ever wondered how to use multiple CTEs in one SQL query? Read this article and find out about recursive CTEs. After learning common table expressions or CTEs, a natural question is “Can I use several CTEs in one query?” Yes, you can! And you can do it quite easily, especially if you already have some basic knowledge of CTEs. Whether you know a bit about CTEs or you’re entirely new to the CTE world, reading about what a CTE is is always a good start. Read more 25 Aug 2020 Tihomir Babic How to Calculate the Length of a Series with SQL What is a time series and why bother to calculate its length using SQL? How do we calculate the length of a series in SQL? I can answer that in two words: window functions! Yes, you’ll need some knowledge of SQL window functions to calculate series length. But what is a time series, and why would you want to find out how long it is? What Is a Series? Read more 5 Aug 2020 Tihomir Babic Who Should Learn SQL Window Functions? Do you want to learn how SQL window functions can help you at your job? This article will show you examples from various business applications where they can be very useful. I won’t be explaining what SQL window functions are in this article, but rather how to use them. If you’re not familiar with window functions or their syntax, don’t worry. Here’s an article that can help you with an introduction to SQL window functions. Read more «« « 1 2 3 … 6 7 8 » »»