Oracle Database SQL — Question 131

Which two are true about unused columns? (Choose two.)

Answer options

• A. Setting an indexed column to unused results in an error.
• B. You can query the data dictionary to see the names of unused columns.
• C. You can specify multiple column names in an ALTER TABLE...SET UNUSED statement.
• D. If you set all the columns of a table to unused, the table is automatically dropped.
• E. CASCADE CONSTRAINTS must be specified when setting a column to unused if that column is referenced in a constraint on another column.

Correct answer: C, E

Explanation

Option C is correct because you can indeed specify multiple column names when using the ALTER TABLE...SET UNUSED statement. Option E is also correct as it is necessary to include CASCADE CONSTRAINTS if the unused column is part of a constraint on another column. Options A, B, and D are incorrect as they misrepresent the behavior of unused columns in the database.