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Articles
Cookbook
28 May 2021
Andrew Bone
UNION vs. UNION ALL in SQL: What’s the Difference?
UNION and UNION ALL are both used to retrieve records from multiple tables. This article will detail the differences between the two, allowing you to make the best choice for each unique scenario. You can use SQL’s UNION and UNION ALL commands to get data from multiple tables in your database. It’s a common use case, considering that most databases have many tables. Both UNION and UNION ALL are known as set operators.
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27 May 2021
Karolina Niewiarowska
Where Can I Find a Data Analyst Internship?
Are you wondering how to land a data analyst job without any professional experience? This article is the answer! Finding an SQL-related internship – an important part of eventually landing a data analyst job. Internships enrich your CV and, more importantly, help you learn SQL from the practical side. I will tell you where to find data analyst internships and what you should know about them. That's right! To gain experience, you need experience – especially when you’re entering the labor market or embarking on a new career.
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26 May 2021
Ignacio L. Bisso
How to Compute Year-Over-Year Differences in SQL
How did your business do this year compared to last year? The year before? Find out how to use SQL to calculate year to year and month to month differences. Year-over-year (YOY) comparisons are a popular and effective way to evaluate the performance of several kinds of organizations. Year to year differences are easy to understand – e.g. it’s easy to understand that your revenue growth is 35% year to year.
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25 May 2021
Karolina Niewiarowska
How to Keep Focused While Learning SQL
Learning SQL can be a challenge, but it’s one you can handle! I’ve prepared 5 tips to help you stay focused during your learning journey. By choosing the right methods and tricks, you can achieve your goals! If you’re interested in learning SQL, I bet that you are a very ambitious person who wants to constantly develop. You may even be taking your first steps in your career. I don't think I need to explain to you the obvious advantages of learning how to operate database systems; Data is everywhere, applies to everyone, and is increasing by the day.
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21 May 2021
Tihomir Babic
8 Best SQL Window Function Articles
Do you need a starting point for learning SQL window functions? Not sure which articles provide a solid foundation? We dove into the internet rabbit hole and found the eight best articles dealing with window and analytic functions. There are plenty of articles dealing with SQL window functions. Type those words into Google and you’ll find a huge number of articles returned. Reading articles is a good start if you want to learn something about window or analytic functions in SQL – provided, of course, that the articles you choose are trustworthy and up to date.
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20 May 2021
Martyna Sławińska
What’s the Difference Between UNIQUE and DISTINCT in SQL?
We use the words unique and distinct interchangeably in our day-to-day life. However, these words play very different roles in SQL. Let’s find out what is so different about them and how we can use them in SQL. Despite the words unique and distinct being synonyms, they cover very different things in SQL. The UNIQUE keyword in SQL plays the role of a database constraint; it ensures there are no duplicate values stored in a particular column or a set of columns.
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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.
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18 May 2021
Andrew Bone
How to Use Aliases in SQL Queries
An SQL alias is useful for simplifying your queries and making the query and its result more readable. This article explains why and how you can use aliases in your SQL queries. You can temporarily rename a table or a column by giving it another name. This is known as an SQL alias. It’s a temporary change that does not affect the actual table name in the database. A temporary table name can also be called a correlation name.
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14 May 2021
James Wondrasek
How to Use Comparison Operators with NULLs in SQL
The SQL NULL value serves a special purpose. It also comes with counterintuitive behaviors that can trip up SQL beginners or even experienced programmers. Learn how to avoid these problems when you use NULL with comparison operators. This article is going to help you master best practices for crafting SQL queries that work with NULL values and use comparison operators ( =, <>, <, > ) – which, if you have written any SQL queries before, you know is just about every query you will ever write!
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13 May 2021
Kateryna Koidan
A Detailed Guide to SQL ORDER BY
It’s often necessary to display the output of SQL query in specific order rather than arbitrarily. In this article, I’ll explain the many ways you can do it with the SQL ORDER BY clause. To sort records in SQL, you’ll need to use the ORDER BY clause. In this article, I’ll explain in detail how to use ORDER BY to sort output by one or more columns, in ascending (A-Z) or descending (Z-A) order, and by using existing column(s) or using column(s) calculated by an aggregate function.
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