Blog Posts

Learn SQL Views in 30 Minutes

Views aren’t complicated – if you’ve got half an hour, we’ll get you started writing SQL queries using views! Let’s start by answering the question “What is a view in SQL?’. A view is a database object (as is a table, an index, or a stored procedure). Like a table, you can query a view and extract the information in it. It can be used in the FROM clause of a SELECT, and you can reference view columns in clauses

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Organize Your SQL Queries with CTEs

Common table expressions (CTEs) allow you to structure and organize your SQL code. Being able to write organized queries is a necessity when you begin to move deeper into SQL, so if you want to become an SQL master, you need to know CTEs. The CTE has been part of standard SQL for some time now. CTEs – which are also called WITH statements – are available in all major RDBMS. When you use a CTE, it’s quicker and easier

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SQL Window Functions By Explanation

In our previous post, we explained how SQL window functions work by example. We started with some very simple, basic functions. Let’s extend it by explaining subclauses in window functions. SQL window functions are a great way to compute results from a set of rows rather than a single row. As you know from our first article, the “window” in window function refers to the set of rows. We showed you some examples of simple window functions like RANK and

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Long SQL Query vs. Recursive SQL Query

Recursion is one of the central ideas in computer science. We can define it as a method for solving problems where the solution of the problem depends on solving a smaller instance of a problem. If this sounds complicated do not fret, in this article we will learn about recursion in SQL that you can practice and deepen in Vertabelo Academy. Recursion is a way of solving hierarchical problems we find in data with common SQL. These types of queries

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High Performance Statistical Queries: Linear Dependencies Between Continuous Variables

In my previous articles, I dealt with analyses of only a single variable. Now it is time to check whether two variables of interest are independent or somehow related. For example, a person’s height positively correlates with shoe size. Taller people have larger shoe sizes, and shorter people have smaller shoe sizes. You can find this and many more examples of positive associations at: A negative association is also possible. For example, an increase in the speed at which

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An Illustrated Guide to Multiple Join

So far, our articles in the “An Illustrated Guide” series have explained several join types: INNER JOINs, OUTER JOINs (LEFT JOIN, RIGHT JOIN, FULL JOIN), CROSS JOIN, self-join and non-equi join. In this final article of the series, we show you how to create SQL queries that match data from multiple tables using one or more join types. Join Types in SQL Queries Before we start discussing example SQL queries that use multiple join types, let’s do a short recap

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