September 2004
Beginner to intermediate
388 pages
6h 34m
English
Now that we have seen how tables are combined with join queries and subqueries, we turn our attention to another type of complex query. The SQL procedure provides users with several table operators: INTERSECT, UNION, OUTER UNION, and EXCEPT, commonly referred to as set operators. In contrast to joins and subqueries where query results are combined horizontally, the purpose of each set operator is to combine or concatenate query results vertically.
The INTERSECT operator creates query results consisting of all the unique rows from the intersection of the two queries. Put another way, the intersection of two queries (A and B) is represented by C, indicating that the ...
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