Exam 1z0-071 topic 1 question 21 discussion

Actual exam question from Oracle's 1z0-071

Question #: 21
Topic #: 1

[All 1z0-071 Questions]

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

A. A query can return data from unused columns, but no DML is possible on those columns.
B. Unused columns retain their data until they are dropped.
C. Once a column has been set to unused, a new column with the same name can be added to the table.
D. The DESCRIBE command displays unused columns.
E. A primary key column cannot be set to unused.
F. A foreign key column cannot be set to unused.

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Suggested Answer: BC 🗳️

by Rik92 at Jan. 25, 2023, 8:38 a.m.

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yolanda_suny

5 months, 2 weeks ago

Selected Answer: BC

Option B: "Unused columns retain their data until they are dropped." This is correct. Unused columns keep their data until they are explicitly removed from the table. Setting a column to unused does not immediately delete its data; it only marks the column as unavailable. Option C: "Once a column has been set to unused, a new column with the same name can be added to the table." This is correct. Once a column is marked as unused, you can add a new column with the same name to the table, because the unused column is effectively 'removed' from the table’s structure in a logical sense.

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CMjer

1 year, 8 months ago

Selected Answer: BC

Note on C: you can add the same name and data type as unused column even if it's not dropped. Tested and it works.

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Makub

1 year, 11 months ago

I tested, Unused can be added on primary key. Desc does not display unused column. not does select query.

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Rik92

2 years ago

B C. Note on C. You can only add a new column with the same name as long as it's a different data type until the UNUSED is dropped.

upvoted 2 times

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