Question

Which of the following DROP INDEX statements would give a notice if the index does not exist but not an error?

a) DROP INDEX myindex RESTRICT;
b) DROP INDEX myindex;
c) DROP INDEX CONCURRENTLY myindex;
d) DROP INDEX IF EXISTS myindex;

Answer 1

D) 'DROP INDEX IF EXISTSThe myindex;' SQL statement will give a notice instead of an error if the index doesn't exist, as the IF EXISTS clause provides a conditional check before attempting to drop the index.

Step-by-step explanation:

The DROP INDEX statement that would give a notice if the index does not exist but not an error is: d) DROP INDEX IF EXISTS myindex;

This is because the IF EXISTS option is specifically designed to check whether the referenced index exists before attempting to drop it. If the index does not exist, instead of returning an error, which could interrupt script execution or transaction processing, the command produces a notice.

This ensures that the SQL statement will be tolerant of the situation where the index has already been removed or was never created, which can be helpful in scripts or programs that might be run multiple times or under varying conditions.

Other options like a) DROP INDEX myindex RESTRICT, b) DROP INDEX myindex, and c) DROP INDEX CONCURRENTLY myindex do not include the conditional check and would typically result in an error if the index does not exist.