September 2004
Beginner to intermediate
388 pages
6h 34m
English
Content preview from PROC SQL: Beyond the Basics Using SAS®
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7.4. Cartesian Product Joins
As mentioned previously, the Cartesian product (or cross join) represents all possible combinations of rows and columns from the joined tables. To be exact, it represents the sum of the number of columns of the input tables plus the product of the number of rows of the input tables. Put another way, it represents each row from the first table matched with each possible row from the second table, and so on and so forth. For example, if you performed a joint operation on one table consisting of 100,000 rows and a second table of 10,000 rows, you would get a Cartesian product of 10 million rows.
Although the Cartesian product serves a very useful purpose in the relational model, it is essentially meaningless for a user ...
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