What is necessary for your query on an existing view to execute successfully?

  1. The underlying tables must have data.

  2. You need SELECT privileges on the view.

  3. The underlying tables must be in the same schema.

  4. You need SELECT privileges only on the underlying tables.


Correct Option: D

AI Explanation

To answer this question, you need to understand the concept of views in databases.

A view is a virtual table that is based on the result of a query. It does not store any data itself but instead retrieves data from the underlying tables whenever it is accessed.

Now let's go through each option to understand why it is correct or incorrect:

Option A) The underlying tables must have data - This option is incorrect because a view can still be executed successfully even if the underlying tables do not have data. The view will return an empty result set in such cases.

Option B) You need SELECT privileges on the view - This option is incorrect because having SELECT privileges on the view alone is not sufficient for the query to execute successfully. You also need SELECT privileges on the underlying tables from which the view is derived.

Option C) The underlying tables must be in the same schema - This option is incorrect because the underlying tables can be in different schemas and the view can still be executed successfully. The schema of the view itself is what matters.

Option D) You need SELECT privileges only on the underlying tables - This option is correct. In order to execute a query on an existing view successfully, you need to have SELECT privileges on the underlying tables from which the view is derived. This is because the view retrieves data from these tables when it is accessed.

The correct answer is D) You need SELECT privileges only on the underlying tables. This option is correct because having SELECT privileges on the underlying tables is necessary for the query on the view to execute successfully.

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