Joining Data in SQL

Overview

Level up your SQL knowledge and learn to join tables together, apply relational set theory, and work with subqueries.

Joining data is an essential skill that enables us to draw information from separate tables together into a single, meaningful set of results. Learn to supercharge your queries using table joins and relational set theory in this course on joining data. In this course, you’ll learn how to work with more than one table in SQL, use inner joins, outer joins, and cross joins, leverage set theory, including unions, intersect, and except clauses, and create nested queries. Every step is accompanied by exercises and opportunities to apply the theory and grow your confidence in SQL.

Syllabus

Introducing Inner Joins

In this chapter, you’ll be introduced to the concept of joining tables and will explore all the ways you can enrich your queries using joins—beginning with inner joins.

Outer Joins, Cross Joins and Self Joins

After familiarizing yourself with inner joins, you will come to grips with different kinds of outer joins. Next, you will learn about cross joins. Finally, you will learn about situations in which you might join a table with itself.

Set Theory for SQL Joins

In this chapter, you will learn about using set theory operations in SQL, with an introduction to UNION, UNION ALL, INTERSECT, and EXCEPT clauses. You’ll explore the predominant ways in which set theory operations differ from join operations.

Subqueries

In this closing chapter, you’ll begin by investigating semi-joins and anti-joins. Next, you'll learn how to use nested queries. Last but not least, you’ll wrap up the course with some challenges!