In this chapter, you learned about the types of table joins, including INNER, OUTER, FULL, and advanced joins, such as the cross, natural, and self joins.
Additionally, you learned about set theory and how to combine queries using operators such as UNION and UNION ALL. You also learned about intersection and differences when combining queries.
Lastly, you learned about optimizing your query when it contains multiple tables, using the EXPLAIN operator, and you saw how you could either change your query or add indexes to improve your query.
In the next chapter, you will learn how to modify data in tables. This includes learning how to use INSERT, UPDATE, and DELETE statements. You will also learn about SQL transactions, which help to better control the modification of data. Additionally, you will learn how to modify table structures.