Which three statements are true about using an invisible column in the PRODUCTS table?

Examine the following command:

CREATE TABLE (prod_id number (4),

Prod_name varchar2 (20),

Category_id number (30),

Quantity_on_hand number (3) INVISIBLE);

Which three statements are true about using an invisible column in the PRODUCTS table? (Choose three.)
A . The %ROWTYPE attribute declarations in PL/SQL to access a row will not display the invisible column in the output.
B . The DESCRIBE commands in SQL *Plus will not display the invisible column in the output.
C . Referential integrity constraint cannot be set on the invisible column.
D . The invisible column cannot be made visible and can only be marked as unused.
E . A primary key constraint can be added on the invisible column.

Answer: A,B,E

Explanation:

AB: You can make individual table columns invisible. Any generic access of a table does not show the invisible columns in the table.

For example, the following operations do not display invisible columns in the output:

* SELECT * FROM statements in SQL

* DESCRIBE commands in SQL*Plus

* %ROWTYPE attribute declarations in PL/SQL

* Describes in Oracle Call Interface (OCI)

Incorrect:

Not D: You can make invisible columns visible.

You can make a column invisible during table creation or when you add a column to a table, and you can later alter the table to make the same column visible.

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