choose three
Which three statements are true about indexes and their administration in an Orade database?
A) An INVISIBLE index is not maintained when Data Manipulation Language (DML) is performed on its underlying table.
B) An index can be created as part of a CREATE TABLE statement.
C) A DROP INDEX statement always prevents updates to the table during the drop opeaton
D) A UNIQUE and non-unique index can be ceated on the same table colunn
E) A descending index is a type of funcion-based index
F) If a query filters on an indexed column then it will always be used during execution of the query
Answer：BCE
(Analysis: construction of the table when you can create an index; the table when the lock will do drop index;
Creating an index in descending order:
create index idx_emp_ename on emp(ename DESC) ;
The index is created, not necessarily will be used in the query time, a lot of factors involved.
)