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  • Bipin Hattiangadi thinks this is interesting:

Hmmm…there are only 18 employees and 3 different departments, so how did the result set end up with 54 rows? Looking more closely, you can see that the set of 18 employees is repeated three times, with all the data identical except for the department name. Because the query didn’t specify how the two tables should be joined, the database server generated the Cartesian product, which is every permutation of the two tables (18 employees × 3 departments = 54 permutations). ...

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