If the number of leaf blocks of index , scanned is less than 5000 then degree of parallelismis 2?

If the number of leaf blocks of index , scanned is 50000-250000 then what is the degree of parallelism is 16 ?

NOLOGGING is used to reduce redo log generation ?

The purpose of comments is that someone that has never worked on the project before. They would need to underderstand precisely where changes has been done, why those changeswere made, and exactly what the change was.

HINTS should be used to parallelise an operation if the operation is FULL TABLE SCAN ?

BITMAP INDEX is used in situations where the index is created after the table or partition is populated ?

UNION or UNION ALL should be avoided ?

In case of any deployment you if we need to backup data anywhere there must be a clear plan to remove this later. ?

For creating a table named T1 do we need to check whether that table exist or not ?

Make sure that every SQL that will run in your PL/SQL writes it’s elapsed time to your log file?

Business Logic comments is required for any SQL