【多选题】
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 t he output.
C Referential integrity constraint cannot be set on t he 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 t he invisible column.
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