Articles Cookbook
1 Dec 2021
LearnSQL.com Team

New Monthly SQL Practice for December 2021!

If you are a more advanced SQL user who is comfortable writing complex JOINs, you can check your knowledge with December's SQL Practice. Every month on LearnSQL.com, you'll find a new challenge to solve. Maybe this is the first time you've come across our Monthly SQL Practices. LearnSQL.com offers one SQL Practice each month: basic levels on even-numbered months and advanced levels on odd-numbered months. Each SQL Practice takes about an hour to complete and contains 5–10 exercises to help you hone your skills.
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26 Nov 2021
András Novoszáth

Here’s Why You Should Use SQL for Sales Analytics

Would you like to understand how your sales efforts play out so that you know where to put your focus? Do you want to empower your sales teams with sales analytics? This article shows you how you can use SQL to use your sales data to your advantage. If you work in sales, understanding the activities that produce results has financial consequences for you, your team, and your company. This is where sales analytics can really help you.
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25 Nov 2021
Kateryna Koidan

5 Best Practices for Writing SQL JOINs

These best practices for SQL JOINs will help you make readable SQL queries that deliver accurate, clear, and understandable output. Considering that relational databases are built around related tables, it’s no wonder that SQL JOINs – which allow you to combine information from multiple tables – are one of the primary skills acquired by SQL newbies. SQL JOINs course by LearnSQL.com is the perfect place to refresh your knowledge about JOINs.
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24 Nov 2021
Tihomir Babic

Top 5 SQL CTE Interview Questions

Here are five questions (and solutions!) on CTEs you’ll (probably) be asked at an interview. I’m not saying you will get these SQL CTE interview questions at every job interview. But when you do, they are probably along the lines of the five I’m about to show here. Other than theoretical questions about CTEs, there are not that many variations in the CTE scenarios evaluated by interviewers. Go through these five examples, and you get a good foundation for acing your interview!
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18 Nov 2021
Kateryna Koidan

5 SQL Subquery Examples

SQL subqueries are basic tools if you want to communicate effectively with relational databases. In this article, I provide five subquery examples demonstrating how to use scalar, multirow, and correlated subqueries in the WHERE, FROM/JOIN, and SELECT clauses. A subquery, or nested query, is a query placed within another SQL query. When requesting information from a database, you may find it necessary to include a subquery into the SELECT, FROM , JOIN, or WHERE clause.
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18 Nov 2021
Jakub Romanowski

Black Week 2021 is Here!

We know you've been waiting for it, and it's finally here: Black Week, and with it, a great promotion for our SQL courses. This is the best offer in the history of LearnSQL.com! Sometimes we surprise ourselves. Last year's Black Week promotion on theAll Forever Plan and individual courses was great, many people took advantage of it, and we thought it would be hard to come up with something better.
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16 Nov 2021
Kamila Ostrowska

SQL for Startups – Do You Need It?

If you’ve been wondering whether to use SQL in your startup, it’s probably high time to do so. SQL can be an amazing tool for small, fast-growing businesses. But don’t worry if you’re unfamiliar with SQL for startups. Maybe you are not sure what SQL is all about. Don’t worry; you don’t have to make any decisions this second! First, answer these questions: Can you think of any data related to your business – prices, clients, details about clients, production details, budget, costs, strategy, or anything else?
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11 Nov 2021
Martyna Sławińska

What Are Aggregate Functions in SQL, and How Do I Use Them?

Data is your source of knowledge. And thanks to SQL aggregate functions, you can extract the precise knowledge you need from your data efficiently. Read along to find out more. The core SQL aggregate functions are the following: COUNT(column_name | *) returns the number of rows in a table. SUM(column_name) returns the sum of the values of a numeric column. AVG(column_name) returns the average value of a numeric column.
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10 Nov 2021
Jakub Romanowski

Interviewing Data with Anthony DeBarros, Author of Practical SQL

Some make model ships, others collect stamps. I read SQL books. I've read a lot of them, but only a very few deserve to be called really good. Some of them were included in my last year's Six Favorite SQL Books list. The good news is that one of them just got a new release. It was great, even better than the previous edition! Moreover, I was able to talk to its author, Anthony DeBarros.
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9 Nov 2021
Himanshu Kathuria

How to Write a WHERE Clause in SQL

We explain how to use the SQL WHERE clause with practical examples. If you have just started learning SQL and want to know how to retrieve or work with only a specific portion of the data stored in your tables, then this article is for you! The SQL WHERE clause is something you must master if you wish to use SQL for working with data. It is arguably one of the most basic and must-learn constructs of SQL.
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