Sams Teach Yourself SQL in 24 Hours, Second Edition

Summary

You have learned that indexes can be used to improve the overall performance of queries and transactions performed within the database. Database indexes, like an index of a book, allow specific data to be quickly referenced from a table. The most common method for creating indexes is through use of the CREATE INDEX command. There are different types of indexes available among various SQL implementations. Unique indexes, single-column indexes, and composite indexes are among those different types of indexes. There are many factors to consider when deciding on the index type used to best meet the needs of your database. The effective use of indexes often requires some experimentation, a thorough knowledge of table relationships and data, ...