Head First SQL, 2nd Edition

Chapter 9. Joins and Unions: Multiple-table Operations

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Welcome to a multi-table world. It’s great to have more than one table in your database, but you’ll need to learn some new step sequences to get your tables to partner with each other. Joins help you reconnect all the data you’ve spread out. And as you’ll soon learn, there are several different join maneuvers for pairing your tables. The words cross join, inner join, left join, right join, and full outer join may not glide through your mind just yet, but by the end of this chapter, you’ll know them well enough to pick the best join for scoring big with the judges. You’ll also meet the self join for that solo work and UNION to combine the results of multiple queries. With these new tricks under your skates, you’ll soon know how to get all of your data back together again, ...