27 Jan 2021 Agnieszka Kozubek-Krycuń Why Aren’t SQL Window Functions Allowed in GROUP BY? It’s true – the SQL order of operations means window functions aren’t allowed in GROUP BY. But you can use them anyway with this special trick. SQL window functions are one of the language’s most powerful features. However, the syntax of window functions is not easy to master. It has lots of details that can cause beginners to stumble. One of the most common traps is trying to use window functions in GROUP BY. Read more 14 Jan 2021 Agnieszka Kozubek-Krycuń Monthly SQL Challenges in 2021 Did you know that LearnSQL.com provides a monthly SQL Challenge? Every month, we publish a new set of SQL practice exercises. Find out what to expect from our SQL challenges in 2021. Here at LearnSQL.com, we believe that the best way to learn SQL is through practice. After all, writing SQL is a practical skill. That’s why all our SQL courses (and there are over 30 of them!) are interactive: You learn SQL by writing SQL code. Read more 8 Dec 2020 Agnieszka Kozubek-Krycuń The History of SQL Standards Has the SQL standard changed in the 30+ years it's been around? Absolutely! Learn about the journey from SQL-86 to modern SQL, today’s standard data language. SQL was created in the early 1970s by IBM. In 1974, Donald Chamberlin and Raymond Boyce published the article SEQUEL: A Structured English Query Language, which introduced SQL to the world. The article contained the BNF grammar (a detailed technical description of the language syntax) for the language, which IBM later thought was a mistake. Read more 2 Dec 2020 Agnieszka Kozubek-Krycuń SQL Technologies Are More Common Than You Think Where is SQL being used today? The answers might surprise you! (Hint: SQL technology is basically everywhere.) Is it worth learning SQL? After all, the language was created in the 1970s. Is it still relevant today? The list of technologies that support SQL is very long – and it’s growing. Read on to find out what kinds of programs use SQL. SQL in Databases Relational Databases = SQL Databases It’s no surprise that SQL is used in relational databases. Read more 17 Nov 2020 Agnieszka Kozubek-Krycuń The History of SQL – How It All Began Who created SQL and why? Find out in this article! Are you learning SQL? Or are you about to take the first step towards working with databases? Great decision! Either way, it's worth knowing the history of SQL – where it came from, who came up with it, and why. Here’s a brief history of SQL, starting with its foundational concept: the database. Ted Codd and the Relational Data Model The first computer databases appeared in the late 1960s. Read more 6 Oct 2020 Agnieszka Kozubek-Krycuń Five Essential Features of a Good SQL Course: What to Look for When Choosing a Course for You There are many different platforms offering SQL courses. If you’re a beginner, it may be difficult to choose the right one for you. Find out what we think are the essential features of a good SQL course. Remember, if you make a poor choice at the beginning, you may get discouraged or get into bad habits that will impact your work down the line. What Is SQL? SQL, or Structured Query Language, is a programming language you use to talk to databases. Read more 10 Sep 2020 Agnieszka Kozubek-Krycuń Behind the Scenes at LearnSQL.com: How Our SQL Courses Are Created Take a peek behind the scenes and learn our secret for creating great SQL courses! Have you ever wondered how LearnSQL.com courses are created? Are we looking at a lot of hard work or just a bit of magic? Or maybe both? Here’s a hint: we rely on proven methods to create user-friendly online courses. But it’s not easy! Read on to see the 8 steps we take when creating a new SQL course. Read more 7 Jul 2020 Agnieszka Kozubek-Krycuń What Is a SQL Dialect, and Which one Should You Learn? SQL, standard SQL, SQL Server, MySQL, PostgreSQL, Oracle, … You’d like to learn SQL, but you feel overwhelmed with keywords and you don’t know where to start. Let’s explain what each of those terms mean. SQL Is the Language for Talking to Databases A database is a computer program that can store and process large amounts of data. There are many different vendors of databases. PostgreSQL, MySQL, Oracle, and SQL Server are all database products by different vendors. Read more 17 Apr 2020 Agnieszka Kozubek-Krycuń Why Take the “SQL Basics” Course at LearnSQL.com LearnSQL.com’s interactive “SQL Basics” course teaches the foundations of SQL. Discover why we built this online course, our philosophy behind it, and what it contains! What Is SQL, and Why Should You Learn It? SQL is a language used to talk to databases, computer programs that hold data and can process it efficiently. SQL can select data from a database and perform various computations on the data, be they simple or complex. Read more 2 Apr 2020 Agnieszka Kozubek-Krycuń How to Get the First Day of the Week in SQL Server This is additional content for the LearnSQL.com course Customer Behavior Analysis in SQL Server. This interactive course will teach you how to analyze customer lifecycle in a SQL database in over 70 hands-on exercises. You will learn how to find out compare registration rates between periods of time, compute conversion rates in SQL, compare customer cohorts, analyze customer activity and customer churn over time. This course is essential for anyone doing customer analysis in their job. Read more «« « 1 2 » »»