19 May 2021 Tihomir Babic What Is Advanced SQL? Are you confused about advanced SQL skills? What are they? This article will explain what advanced SQL can mean, especially as we use it on LearnSQL.com. I’m sure you find the phrases ‘advanced SQL skills’ or ‘advanced SQL topics’ very often. You read one article about advanced SQL and you’re happy with how easy these advanced topics seem to be. Then you talk to someone and you see they consider everything you know as basic SQL knowledge. Read more 22 Apr 2021 Tihomir Babic Training SQL JOINs Doesn't Have To Be Difficult How can you train your SQL JOIN skills? And where can you do this? Also, why should you even learn SQL JOINs in the first place? All of these questions will soon be answered. One of the positive sides of the internet era is information abundance. One of the negative sides of the internet era is, well, information abundance. The amount of information and knowledge available can be overwhelming. Read more 20 Apr 2021 Tihomir Babic Hierarchical Data and How to Query It in SQL How do you recognize hierarchical data, and how do you query it? Two common SQL questions are about to be answered. Querying hierarchical data is a rather common situation if you’re working with SQL and relational databases. Not that hierarchical data is something mystical and rare; on the contrary, it’s everywhere. So why is hierarchical data so challenging when it comes to relational databases? Mainly, the difficulties occur in translating hierarchical data to relational database principles. Read more 6 Apr 2021 Tihomir Babic How to Find the Next Non-NULL Value in SQL You need to find the next non-NULL value in a time series, but you don’t know how. Can you even do that in SQL? Yes, you can! This article will show you what to do. If you work with SQL, you will sooner or later confront NULL values. Having NULLs in a database is almost unavoidable. However, sometimes you want to avoid them in your reports. This is quite often true when you’re analyzing time series data; NULL values mean there’s no data available. Read more 12 Mar 2021 Tihomir Babic SQL JOIN Topics That Require Practice Are you interested in learning how to join tables in SQL? Where do you start? Many JOIN topics require practice. In this article, we’ll explore these topics by writing codes to solve real-life situations. Hopefully, you will learn which JOIN topics require attention. To make it easier for you, the topics are divided into beginner, intermediate, and advanced. Joining two or more tables in SQL lifts data analysis to another level. Read more 5 Mar 2021 Tihomir Babic How to Get Descendants of a Parent in SQL Want to learn how to handle family trees and find descendants of a parent? By reading this article, you’ll learn how to handle hierarchical data. Finding descendants from a parent is a common problem in SQL. If you imagine a family tree, the basic building block that forms the relationships within it is the parent-child relationship. The parent-child relationship is precisely what defines all hierarchical data. Another example of hierarchical data is the manager-employee relationship. Read more 12 Feb 2021 Tihomir Babic 6 Advanced SQL Queries for Analyzing Financial Data Are you an advanced SQL user who’s new to finance? Do you want to learn how to use your knowledge to analyze financial data? The article will give you some guidance. You probably know that SQL is a potent tool for analyzing all sorts of data. The bigger and more complex data, the more beneficial SQL becomes. In certain situations, financial data can be very complicated; producing a sophisticated analysis requires sophisticated tools. Read more 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 7 Jan 2021 Tihomir Babic An Overview of Aggregate Functions in SQL Aggregate functions are commonly used in SQL. This article will lead you through their use and show examples of how they work. SQL aggregate functions are a useful tool, especially for creating reports. They’re not difficult to understand, especially if you have some experience with Excel or similar programs. You’ve probably used aggregate functions like SUM or AVERAGE in a spreadsheet. Even if you only occasionally use them, knowing aggregate functions can help you better understand your data and work more efficiently. 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 «« « 1 2 3 4 » »»