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What is the main difference between the SET UNUSED COLUMN and the DROP COLUMN clauses of the ALTER TABLE command?
Please select the best answer.
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A.
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You can view the data in the unused column and you cannot view the data in a dropped column. |
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B.
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You free up space with DROP COLUMN (but not with SET UNUSED COLUMN). |
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C.
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You can use SET UNUSED COLUMN (but not DROP COLUMN) on a primary key column. |
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D.
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You can specify a list of columns with SET UNUSED COLUMN (but not with DROP COLUMN). |