Database Joins Archives

You’ll find article covering several types of database joins including Inner Joins and Outer Joins.

It is important to learn about both inner and outer joins and they have different matching behavior.

I would start out with our article Introduction to Database Joins.

This first article introduces the concept of joining tables. The focus is going to be more on the type of joins, not necessarily their syntax. The later articles focus on the various types of joins. Through the narrative and examples you’ll become very comfortable with each one.

Some of our more popular articles include:

All the examples for this lesson are based on Microsoft SQL Server Management Studio and the sample databases AdventureWorks and WideWorldImporters. You can get started using these free tools using my guide Getting Started Using SQL Server

What is a Non-Equi Join in SQL and What is its Purpose?

I recently put together a lesson on non-equi joins. It is part of my Join Together Now course. Click here get the course at a discount. A non-equi join can be used to solve some interesting query problems. You can use a non-equi join to check for duplicate value or when you need to compare […]

How to Make a Join Easier to Read using Table Aliases

I recently put together a lesson on table aliases and multi-table joins. It is part of my Join Together Now course. Click here get the course at a discount. You’ll find that as you write more complicated joins, that the SQL can become harder to read, as you’ll need to qualify column with table names […]

Joins versus Subqueries SQL Puzzle

In this puzzle, we’re going to learn about joins versus subqueries. In many queries you can substitute joins and subqueries. Yet, since each has their strengths, it isn’t wise to do so. Once you have worked through this puzzle you see some of the benefits and disadvantages of joins versus subqueries. Solving puzzles is a […]

Learn How to Combine Data with a CROSS JOIN

A cross join is used when you wish to create combination of every row from two tables. All row combinations are included in the result; this is commonly called cross product join. A common use for a cross join is to create obtain all combinations of items, such as colors and sizes. Note: The series […]

What is the Difference between Inner and Outer Joins?

Both inner and outer joins can be used to combine data from two or more tables; however, there are some key differences! Read this article to find out each command’s strengths and when to use them. To get the most of this and our other lessons be sure to practice using the examples! All the […]

What Is the Difference Between a Join and a UNION?

Both Joins and UNIONS can be used to combine data from two or more tables. Read this article to find out each command’s strengths and when to use them. To get the most of this and our other lessons be sure to practice using the examples! All the examples for this lesson are based on […]

Subqueries versus Joins

Joins and subqueries are both be used to query data from different tables and may even share the same query plan, but there are many differences between them. Knowing the differences and when to use either a join or subquery to search data from one or more tables is key to mastering SQL. All the examples […]

Is it possible to use Joins, Subqueries, and Unions in one Query?

A reader recently asked me to help them solve a problem combining data from multiple tables into a single result. What was interesting was that the solution used the three ways to combine data that we have recently covered, namely: JOINS, set operators, and subqueries. Given the comprehensive nature of this problem I thought it […]

Introduction to Outer Joins

Outer Joins Outer joins are used to match rows from two tables. Even if there is no match rows are included. Rows from one of the tables are always included, for the other, when there are no matches, NULL values are included. The series starts with the article Introduction to Database Joins. All the examples for […]

Inner Join Introduction

An inner join is used when you need to match rows from two tables. Rows that match remain in the result, those that don’t are rejected. The match condition is commonly called the join condition. When the match conditions involve equality, that is matching exactly the contents of one column to another, the join is […]

Introduction to Database Joins

One of the biggest issues beginning SQL writers have is being able to write queries that use more than one table, that is to use database joins. In this series of articles we are going to show you how to write a query that combines, or joins, data from more than one table. Once you […]