Articles Cookbook
15 Dec 2017
Dejan Sarka

Statistics in SQL: Dependencies Between Discrete Variables

In my previous article, we looked at how you can calculate linear dependencies between two continuous variables with covariance and correlation. Both methods use the means of the two variables in their calculations. However, mean values and other population moments make no sense for categorical (nominal) variables. For instance, if you denote "Clerical" as 1 and "Professional" as 2 for an occupation variable, what does the average of 1.5 signify?
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12 Dec 2017
Aldo Zelen

Simplify SQL Code: Recursive Queries in DBMS

Hey SQL users! Are you repeating the same query in every report? Are your queries getting too complicated? Use recursive queries to simplify SQL code! Too many SQL reports can lead to clutter on your desktop and in your head. And is it really necessary to code each of them separately? Ad-hoc queries can share much of the same SQL code with managerial reports and even regulatory reports. Suppose you’ve been writing basic SQL code for a while.
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7 Dec 2017
Ignacio L. Bisso

The SQL Coalesce Function: Handling Null Values

You may already know how to return null values in SQL. Now, we’re going to learn how to do the opposite. Though the SQL COALESCE function may seem complex, it’s actually very straightforward and useful. Let’s look at several examples of how the SQL COALESCE function can be used to work with NULL values in SQL. The Need for Coalesce in SQL Before we dive into the SQL COALESCE function in detail, you should understand how NULL values behave in expressions.
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29 Nov 2017
Kacper Skawina

Analyzing Survey Data: Explore Results Using SQL

Excel is a powerful beast that lets you analyze complex data. Yet, operating on big chunks of data can sometimes be a daunting task. Let's take a look at how SQL can help. Today, we'll tackle a common problem with importing data to an SQL database, using a real-life example. Suppose your company conducted a survey on the most popular programming trends and preferences, striving to meet the expectations of its users.
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27 Nov 2017
Ignacio L. Bisso

SQL Date and Interval Arithmetic: Employee Lateness

Computing Tardiness: Date, Time, and Interval SQL Arithmetic In this article, we’re going to discuss some interesting operations we can perform with date-related data types in SQL. The SQL standard, which most relational databases comply with these days, specifies the date-related data types that must be present in relational databases. The most important of such data types are date, time, timestamp, and interval. Here’s a brief rundown of the differences between these data types:
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13 Nov 2017
Aldo Zelen

SQL Reporting Guide for Business Professionals

Working with the financial aspects of large and small enterprises can be a daunting task for a business professional. In this article, we'll look at several ways of constructing the perfect SQL report. You've probably already heard about SQL from your colleagues or in other areas of your career. If you're here, you've likely concluded that learning SQL will make your professional life easier – and you're right!
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9 Nov 2017
Alex Briggs

5 Great Benefits of Learning SQL

If you want your business to succeed, understanding your data is crucial—and that’s why learning SQL is so important. But there are other reasons to learn it that might not be so obvious. In this article, I’ll show you 5 key benefits of learning SQL! Don’t fall for the common trap—analyzing data isn’t just a concern for those competing at national or corporate levels. In fact, all businesses have plenty of data that they can use to potentially improve their workflow.
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25 Oct 2017
Dorota Wdzięczna

16 SQL Interview Questions for Business Analysts

For business analysts, SQL skills are incredibly important. That’s why SQL interview questions are a major part of the hiring process. These questions test key SQL concepts and how they apply to data analysis. In this article, we’ll go over some of the most common SQL interview questions for business analysts. Our goal is to give you the insights you need to do well in your interview and move forward in your career.
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18 Oct 2017
Ignacio L. Bisso

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 like SELECT, WHERE and GROUP BY among other clauses as well.
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16 Oct 2017
Aldo Zelen

How to Organize SQL Queries with CTEs

Common table expressions (CTEs) allow you to structure and organize SQL queries. Knowing how to organize SQL 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 SQL CTE has been part of standard SQL for some time now. CTEs – which are also called WITH statements – are available in all major RDBMS.
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