To produce a meaningful result set without any cartesian products, what is the minimum number of conditions that should appear in the WHERE clause of a that joins 'N' tables?
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4
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3
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N - 1
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N + 1
To solve this question, the user needs to have a basic understanding of SQL joins and how to prevent cartesian products.
When joining N tables, the minimum number of conditions that should appear in the WHERE clause to produce a meaningful result set without any cartesian products is N - 1. This is because each join condition connects two tables, and N tables can be connected by N - 1 join conditions.
Option A (4) and Option B (3) are not correct because they provide specific numbers of conditions that do not apply to all cases. The number of conditions needed depends on the number of tables being joined, which is not specified in the question.
Option C (N - 1) is correct, as explained above.
Option D (N + 1) is incorrect because adding an additional condition would result in a more restrictive query, potentially excluding valid results.
Therefore, the answer is: C. N - 1.
To avoid a Cartesian product when joining N tables, you need at least N-1 join conditions in the WHERE clause. Think of it as a spanning tree over the tables: each join condition connects two tables, and you need N-1 edges to connect N nodes without leaving any table unconnected. If you have fewer than N-1 conditions, at least one table is left unjoined and produces a full Cartesian product with the rest. '4' and '3' are arbitrary fixed numbers that don't scale with N. 'N + 1' overshoots — you never need more conditions than there are 'gaps' between tables, and extra conditions (beyond N-1) are refining filters, not connectivity requirements.