Oracle force indexing with hint method

The first thing to look at is whether your Oracle optimizer is using RBO or CBO,
(1) If Rbo is used, it will be carried out in the order of the rules.
(2) If you are using a CBO, you can modify it using the Hint method.

Syntax:SELECT/*+ Index (table indexname) */
If the table in the query statement uses an alias, the table in the top statement must be an alias, otherwise it does not go to enforce the index.

Example:

Select/*+index (t idx_date) */from  student T  where t.birthday >  to_date (' 2010-12-28 00:00:00 ', ' Yyyy-mm-dd hh24:mi:ss ')  and T.birthday <  to_date (' 2010-12-28 23:59:59 ', ' yyyy-mm-dd hh24:mi:ss ')  

Oracle force indexing with hint method