Articles Cookbook
27 Apr 2021
Martyna Sławińska

What Is the Benefit of Foreign Keys in SQL?

What is a foreign key and why is it so important in relational databases? Learn all the details about foreign keys in this article. One of relational databases’ key features is the ability to link data stored in different tables. These links, called references, essentially act as connections between tables. They are created using the FOREIGN KEY constraint on table columns. In this article, we’ll learn what the FOREIGN KEY constraint does in SQL.
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23 Apr 2021
Andrew Bone

What Is the Role of DISTINCT in SQL?

The DISTINCT keyword in SQL plays an important role in removing duplicate values from your results. This article provides examples showing exactly how DISTINCT works. By default, SQL queries show all the returned rows, including duplicate rows, in the result set. The DISTINCT keyword in the SELECT clause is used to eliminate duplicate rows and display a unique list of values. In other words, the DISTINCT keyword retrieves unique values from a table.
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21 Apr 2021
Andrew Bone

What Do the SQL INTERSECT and MINUS Clauses Do?

Do you know the difference between SQL’s INTERSECT and MINUS clauses and how to use them? You will find examples and explanations in this article. SQL INTERSECT and MINUS are useful clauses for quickly finding the difference between two tables and finding the rows they share. INTERSECT compares the data between tables and returns only the rows of data that exist in both tables. MINUS compares the data between tables and returns the rows of data that exist only in the first table you specify.
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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.
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16 Apr 2021
Himanshu Kathuria

Analyze Small Datasets with SQL

If you think SQL data analysis is useful only when a business is generating millions of rows of data – that SQL cannot help you if you are generating a limited dataset – think again and read on! There is so much talk about how SQL is useful in analyzing Big Data that sometimes the applications of SQL data analysis for small datasets can go unnoticed. Having worked with early-stage businesses – which have just started generating data through daily transactions – as well as big established clients generating terabytes of data, I can tell you for sure that SQL can be an extremely handy tool for just about any business.
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15 Apr 2021
Karolina Niewiarowska

Does Music Improve Work Efficiency?

Do you sometimes have trouble focusing when working or studying SQL? Do you ever lack motivation? I have the perfect solution for you: music for learning SQL! I am excited to tell you about how the right tunes can significantly enhance your efficiency and concentration. Music can soothe the savage beast, they say. It can also inspire action. In general, music is an important element of human life. Most activities are just more enjoyable with background music.
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14 Apr 2021
Kamila Ostrowska

Who Should Learn SQL?

If you learn SQL, will you use it in your current (or dream) job? If you learn it, will it help you with your daily tasks? SQL has so much potential that everyone can benefit from it – including you! Read this article to find out how much you will gain by knowing SQL. I could answer the title question with one word: everyone! But not everyone wants to learn SQL.
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13 Apr 2021
Zahin Rahman

What FULL JOIN Is and When to Use It

Learn about FULL JOIN, how to implement it, how it compares with the other types of SQL JOINs, and some of its unique use cases. Before we jump into FULL JOINs, let’s quickly recap what an SQL JOIN is. At its core, a JOIN combines data from two or more tables within a database. Tables are usually linked together using unique identifiers in each table, i.e. primary and foreign keys.
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9 Apr 2021
Kateryna Koidan

7 SQL JOIN Examples With Detailed Explanations

Do you need to join several tables to get the necessary result set? The SQL JOIN is a basic yet important tool used by data analysts working with relational databases. And I understand it can be difficult to choose from the zillions of introductory guides to joins. In this article, I will focus on real-world examples with detailed explanations. Introduction to JOIN With relational databases, the information you want is often stored in several tables.
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8 Apr 2021
Zahin Rahman

SQL CTE Explained

In this article, you will learn about SQL Common Table Expressions (CTEs). This powerful SQL tool will help you simplify complex queries. Additionally, I will introduce you to the two main types of CTEs and some of their use cases.  CTE Primer The Common Table Expression (CTE) was introduced to standard SQL to simplify long, complex queries (especially joins and subqueries). It is a temporary data set returned by a query that contains data separate from the main query.
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