Question 37

Explanation

The table in read-only is different from DB in read-only.

Since the PRODUCTS table is in read-only mode, you cannot perform any DML (Data Manipulation Language) or DDL (Data Definition Language) operations that modify the table's structure or data.

Analyzing the given commands:

1. CREATE INDEX price_idx ON products (price);
   This will execute successfully.

   • Creating an index does not modify table data, so it is allowed in read-only mode.

2. ALTER TABLE products DROP UNUSED COLUMNS;
   This will fail.

   • Dropping unused columns modifies the table structure, which is not allowed in read-only mode.

3. ALTER TABLE products SET UNUSED (expiry_date);
   This will fail.

   • Marking a column as unused modifies the table structure.

4. ALTER TABLE products DROP COLUMN expiry_date;
   This will fail.

   • Dropping a column changes the schema, which is not allowed.

5. TRUNCATE TABLE products;
   This will fail.

   • TRUNCATE removes all rows, which modifies the data.

When a table is in read-only mode, operations that attempt to modify table data are disallowed. The following operations are not permitted on a read-only table:

All DML operations on the table or any of its partitions

TRUNCATE TABLE
SELECT FOR UPDATE
ALTER TABLE ADD/MODIFY/RENAME/DROP COLUMN
ALTER TABLE SET COLUMN UNUSED
ALTER TABLE DROP/TRUNCATE/EXCHANGE (SUB)PARTITION
ALTER TABLE UPGRADE INCLUDING DATA or ALTER TYPE CASCADE INCLUDING TABLE DATA for a type with read-only table dependants
Online redefinition
FLASHBACK TABLE
The following operations are permitted on a read-only table:
SELECT
CREATE/ALTER/DROP INDEX
ALTER TABLE ADD/MODIFY/DROP/ENABLE/DISABLE CONSTRAINT
ALTER TABLE for physical property changes
ALTER TABLE DROP UNUSED COLUMNS
ALTER TABLE ADD/COALESCE/MERGE/MODIFY/MOVE/RENAME/SPLIT (SUB)PARTITION
ALTER TABLE MOVE
ALTER TABLE ENABLE ROW MOVEMENT and ALTER TABLE SHRINK
RENAME TABLE and ALTER TABLE RENAME TO
DROP TABLE
ALTER TABLE DEALLOCATE UNUSED
ALTER TABLE ADD/DROP SUPPLEMENTAL LOG