What Is an OUTER JOIN?
As we explained in the previous chapter, the SQL Standard defines several types of JOIN operations to link two or more tables or result sets. An OUTER JOIN asks your database system to return not only the rows that match on the criteria you specify but also the unmatched rows from either one or both of the two sets you want to link.
Let’s suppose, for example, that you want to fetch information from the School Scheduling database about students and the classes for which they’re registered. As you learned in the previous chapter, an INNER JOIN returns only students who have registered for a class and classes for which a student has registered. It won’t return any students who have been accepted at the school but haven’t ...
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