Which three statements are true about the DESCRIBE command? (Choose three.)
A. It displays the PRIMARY KEY constraint for any column or columns that have that constraint
B. It can be used from SQL Developer
C. It displays the NOT NULL constraint for any columns that have that constraint
D. It can be used to display the structure of an existing view
E. It displays all constraints that are defined for each column
F. It can be used only from SQL*Plus
BCD