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Articles
Cookbook
19 Nov 2020
Martyna Sławińska
What Is a SQL Constraint?
What are SQL constraints? When and why should you use them? We give examples of common constraints and demonstrate how to apply them. When you’re creating a relational database, you often want to impose certain restrictions on some columns. For example, a column containing a social security number should store only unique values; a column containing a date of birth should not be null, or left empty. These conditions can be ensured by using SQL constraints.
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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.
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13 Nov 2020
Kamila Ostrowska
Practice SQL Before Interviewing a Potential Employee
Has your company grown to the point that you need to hire an SQL expert? Have you found a candidate for the job? How do you prepare for the interview, especially if you don’t know SQL? Don't worry! Follow our suggestions on how to practice SQL. We have tips and tricks to help you feel confident and find the perfect employee. Who You Want To Hire First of all, you need to know the requirements for the new employee.
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12 Nov 2020
Marija Ilic
SQL JOIN Types Explained
What’s the difference between INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN in SQL? When should you use each one? We’ve got your answers right here. You want to combine data from two or more different tables, but you’re not sure how to do it in SQL. No worries. In this article, I will show you how to use the SQL JOIN clause to merge data from two tables.
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11 Nov 2020
Zahin Rahman
Top 7 Online Courses for Data Engineers
This article summarizes the top online courses available for data engineers. We have picks suitable for beginners as well as intermediate learners. If you’re interested in database design and management, check these courses out! Most individuals who aspire to enter the realm of data aim for data scientist or data analyst roles. While these roles are indeed very rewarding because of their tangible links to customers and business direction, the role of data engineers is equally vital for businesses that operate in a data-rich environment.
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10 Nov 2020
Jakub Romanowski
SQL Terms Beginners Should Know
Have you started learning SQL? Do you feel a little lost in the maze of new words and ideas? Here’s a list of 10 absolutely essential SQL terms for beginners. When you start learning SQL, there’s a lot to process. And some of it – even basic SQL terms – gets lost in the shuffle. If this sounds like you, bookmark this article; it will be a handy reference.
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6 Nov 2020
Magdalena Wojtas
Where to Go After Learning SQL Basics
Learning to code is – in general – a lot of fun, for sure. Even after a few years in the IT industry, I still love learning new technologies. And I now know that learning with a good plan is even better than learning without one. This also applies to learning with advanced SQL courses. In this article, I'll show you how learning paths can save you some time and a lot of frustration.
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4 Nov 2020
Jakub Romanowski
Kickstart SQL Learning with Our SQL Basics Course
Updated on: February 19, 2024 Why learn SQL from our interactive online courses? Two reasons: 1) Power up your career. 2) Avoid being a noob. What does it mean to be a noob? “Noob” comes to us from the world of computer games. It’s a combination of “newbie” and “beginner”. It’s not a very nice word. It means that someone has found you an inexperienced player and (even worse) resistant to learning.
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3 Nov 2020
LearnSQL.com Team
SQL Course of the Month – GROUP BY Extensions in SQL
Do you want to develop your SQL skills? Do you want to get more out of your data and prepare better reports and summaries? The answer is learning to use SQL’s GROUP BY extensions. But how should you go about this? I asked the same question to Agnieszka Kozubek-Krycuń, Vertabelo’s Chief Content Officer. As she explains, the secret is in this November’s free SQL Course of the Month: GROUP BY Extensions in SQL.
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1 Nov 2020
LearnSQL.com Team
New Monthly SQL Challenge for November 2020!
Are you ready for a new Monthly Challenge on LearnSQL.com? In November, we invite you to test your SQL skills as you learn about popular regional dishes in the USA. Is this the first time you’ve come across our Monthly Challenges? LearnSQL.com offers one free SQL Challenge each month. Each one contains from 5 to 10 SQL exercises that will help you practice your SQL skills. It takes about an hour (or less!
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