Multiple choice technology databases

A UNION query is which of the following?

  1. Combines the output from no more than two queries and must include the same number of columns.

  2. Combines the output from no more than two queries and does not include the same number of columns.

  3. Combines the output from multiple queries and must include the same number of columns.

  4. Combines the output from multiple queries and does not include the same number of columns.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A UNION query combines results from multiple SELECT statements into a single result set. Key requirements: all queries must have the same number of columns, columns must be in the same order, and data types must be compatible. The 'no more than two' limitation in options A and B is incorrect.

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