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In this chapter, we learned how to query multiple tables using joins. We covered the different types of joins, including inner joins, outer joins, self-joins, left joins, and right joins. We also learned how to use the JOIN ON clause and the GROUP BY clause to combine data from multiple tables.The basic syntax for a join is `SELECT column1, column2, ... FROM table1 INNER JOIN table2 ON column1 = column2;`. In this syntax, "table1" and "table2" are the tables being joined, and "column1" and "column2" are the columns that are common to both tables.We also learned how to use subqueries and joins, which can be used to retrieve data from any number of tables. The syntax for using a subquery in a join is `SELECT column1, column2 FROM table1 WHERE IN (SELECT * FROM subquery);`. In this syntax, "subquery" is the subquery that is used to retrieve data from the top table, and "table1" is the table that the subquery is applied to.Practice exercises were provided at the end of the chapter to give readers a chance to try out their newfound knowledge.
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