In relational database, Index will be the important mechanism for boosting performance.
Index is important like Index for a book that helps you quickly find the pages that you wanted to read, index on the column speeds data retrieval.
CREATE INDEX Statement will look like this:
CREATE [UNIQUE] INDEX [INDEX NAME]
ON TABLE [COLUMN NAME]
Want to create a INDEX on Table Users which is including column names user_fname and user_lname.
CREATE INDEX user_name
ON Users (user_fname, user_lname)