Joining Data in SQL

In the first lesson of this SQL Intermediate course, you’ll learn SQL joins, and unlocking the true power of SQL with more advanced, complex queries. Often times when you’re working with SQL, the data you’d like to be working with is spread out across multiple tables, so being able to combine them efficiently is a critical skill for anyone working with data.

You’ll learn about the four basic types of joins: the inner join, the outer join, the left join, and the right join. Each join covered in this lesson serves a specific purpose, and knowing about the different types of joins increases what you can do with SQL ten-fold.

Not only will you learn how to execute each of these joins, you will also learn what makes them different from each other both syntactically and conceptually.

And of course, you’ll get hands-on practice using each type of join so that you can feel confident in your SQL ability. At this point, you’re well on your way to becoming proficient in writing queries to solve any problem or answer any question.

To facilitate your learning of the different types of joins, you’ll be working with a version of the CIA World Factbook data and using that to find the capital cities that are the most populated.


  • Learn SQL joins are and how to use the four common join types.
  • Learn how to use joins with subqueries to write intermediate queries.
  • Learn how to use joins to answer business questions.

Lesson Outline

  1. Introducing Joins
  2. Understanding Inner Joins
  3. Practicing Inner Joins
  4. Left Joins
  5. Right Joins and Outer Joins
  6. Finding the Most Populous Capital Cities
  7. Combining Joins with Subqueries
  8. Challenge: Complex Query with Joins and Subqueries
  9. Next Steps
  10. Takeaways

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