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What is a subquery?(a) A subquery is a select-from-where expression that is nested within another query(b) A subquery is any query that is nested within another query(c) A subquery is a relation that is externally specified which can be used to handle data in queries(d) A subquery is a condition that excludes all the invalid tuples from the databaseI got this question in an interview for job.This intriguing question comes from Nested Subqueries in portion Introduction to Relational Model and Sql of RDBMS

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Correct ANSWER is (a) A SUBQUERY is a select-from-where EXPRESSION that is nested within another query

Explanation: A subquery is a select-from-where expression that is nested within another query. Common uses for sub-queries are to perform tests for set membership, MAKE set comparisons etc.



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