Which of the following is true about indexes and index desig

Which of the following is true about indexes and index design? a. indexes usually speed up write operations b. a composite index is an index on a single column c. indexes should be created on columns used by WHERE and BY clauses d. an index is created for every foreign key by default

Solution

Answer: Indexes should be created on columns used by WHERE and BY clauses.

Indexes are used for retrieve the records fast. So we have to mention the column names in WHERE clause and By clause in which we created the columns for fast retrieval of the records.