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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?（）
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.

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出自：Oracle认证

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