Joins

Himanshu Kathuria

What Is the OUTER JOIN in SQL?

Even if you are new to SQL, you must have come across the term OUTER JOIN. In this article, I will explain what OUTER JOIN in SQL does. I’ll use some practical examples to demonstrate how it is used in day-to-day SQL applications. If you want to use SQL for practical purposes, learning the different JOINs is extremely important. In fact, you will be using a JOIN in just about every second query you write.

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.

Kateryna Koidan

How to Join Only the First Row in SQL

In your projects, you may encounter situations when you have many orders corresponding to one customer or many temperature observations corresponding to the same location, but you only need to join the first row with the most recent order or the most recently observed temperature to the corresponding record in another table. In this article, I’ll go through several ways to do this in SQL. The best way to practice basic and advanced SQL is our interactive SQL Practice Set course.

Kamila Ostrowska

Best Places to Practice SQL JOINs Online

You’ve just started your journey with SQL and you’re not sure what a JOIN is or where to use it. Don’t worry! In this article, you will find out what JOINs are and where you can practice them online. If you have just started learning SQL, you have a lot of topics to cover before you can call yourself a data professional. If you are serious about using SQL, you’ll have to understand JOIN – what it does, when you can use it, and what its different variants do.

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.

Jakub Romanowski

Where to Practice JOINs in MS SQL Server

Are you tired of looking for exercises that will help you master SQL JOINs in MS SQL Server? Find out about an online course that will take your JOINs skills to the next level! There are tons of MS SQL Server courses out there. Some are good, although they often lack the most important thing ... the possibility of practicing what you learn with interactive exercises. This is one of the main reasons I advise people (especially beginners) not to learn SQL exclusively from YouTube clips.

Martyna Sławińska

What Is a Self Join in SQL? An Explanation With Seven Examples

The self join is a popular special case of the SQL JOIN. While most JOINs link two or more tables with each other to present their data together, a self join links a table to itself. This is usually done by joining a table to itself just once within a SQL query, but it is possible to do so multiple times within the same query. Typically, each table in a database stores a specific type of information.

Marija Ilic

How to Join the Same Table Twice

JOIN is one of the most common statements in SQL. As you may know, it is used to join and combine data from two or more tables into one common data set. In this article, I’m going to discuss special types of joins? in which you combine the same table twice—including joining a table to itself, also known as the self join. When and why do you need to do this?

LearnSQL.com Team

SQL JOIN Cheat Sheet

Download this 2-page SQL JOIN Cheat Sheet in PDF or PNG format, print it out, and stick to your desk. The SQL JOIN Cheat Sheet provides you with the syntax of different JOINs, and examples. You can download this cheat sheet as follows: Download 2-page SQL JOIN Cheat Sheet in PDF format (A4) Download 2-page SQL JOIN Cheat Sheet in PDF format (Letter) Download 1-page SQL JOIN Cheat Sheet in PDF format (A3) Download 1-page SQL JOIN Cheat Sheet in PDF format (Ledger) SQL JOINs Cheat Sheet JOINING TABLES JOIN combines data from two tables.

Kateryna Koidan

Can you Join two Tables Without a Common Column?

Yes, you can! The longer answer is yes, there are a few ways to combine two tables without a common column, including CROSS JOIN (Cartesian product) and UNION. The latter is technically not a join but can be handy for merging tables in SQL. In this article, I’ll guide you through the different solutions with examples. When Do you Need to Join Tables Without a Common Column? Beginners just getting started with SQL are usually introduced to standard equi joins, in which two tables are combined by a common column.

Kateryna Koidan

What's the Difference Between Having Multiple Tables in FROM and Using JOIN?

What’s your approach to joining tables in SQL? In this article, we discuss two approaches and explain why many SQL developers have a definite preference for JOIN. Do you prefer to list multiple tables in FROM and use WHERE to set the join conditions? Or do you use the JOIN keyword? SQL supports both, but there are significant differences between them. Let’s look at each one in detail and then discuss why JOIN is generally preferred.

Kateryna Koidan

Practical Examples of When to Use Non-Equi JOINs in SQL

If you think that two tables in SQL can be joined only using the common field, you will be excited to learn that there are other ways of joining. Non-equi JOINs use different kinds of comparison operators in the JOIN condition. In this article, I’ll guide you through non-equi JOIN examples to show the common use cases for this type of JOIN. Equi JOIN vs. Non-Equi JOIN How do you usually join two tables in SQL?

Zahin Rahman

How to Learn SQL JOINs

JOINs are one of the most fundamental and commonly used SQL commands for manipulating and querying real-world data sets. They are also one of the more challenging SQL topics to master! In this article, you’ll learn an effective strategy to learn the different types of SQL JOINs. When data is stored in a single table, we can easily retrieve rows and get all the information we need. But when businesses scale, so does their data.

Dorota Wdzięczna

Subquery vs. JOIN

One of the challenges in writing SQL queries is choosing whether to use a subquery or a JOIN. There are many situations in which a JOIN is the better solution, and there are others where a subquery is better. Let’s consider this topic in detail. Subqueries are used in complex SQL queries. Usually, there is a main outer query and one or more subqueries nested within the outer query.

Kamil Bladoszewski

How to Join 3 Tables (or More) in SQL

Using JOIN in SQL doesn’t mean you can only join two tables. You can join 3, 4, or even more! The possibilities are limitless. The best way to practice SQL JOINs is LearnSQL.com's interactive SQL JOINs course. It contains over 90 hands-on exercises that let you refresh your SQL JOINs knowledge. It covers a wide range of topics from simple 2-table JOINs, through joining multiple tables and using OUTER JOINs, to joining a table with itself.

Kateryna Koidan

How to LEFT JOIN Multiple Tables in SQL

Can you LEFT JOIN three tables in SQL? Yes, indeed! You can use multiple LEFT JOINs in one query if needed for your analysis. In this article, I will go through some examples to demonstrate how to LEFT JOIN multiple tables in SQL and how to avoid some common pitfalls when doing so. The best way to practice different types of joins is our interactive SQL JOINs course. It contains over 90 hands-on exercises that cover simple 2-table joins, joining multiple tables, LEFT JOIN, FULL JOIN, and many more.