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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