What is the purpose of the SQL command 'ORDER BY'?

The purpose of the SQL command 'ORDER BY' is to sort the results returned by a query. When a user executes a query to retrieve data from a database, they may want that data to be presented in a specific order, such as alphabetically, numerically, or by date. The 'ORDER BY' clause facilitates this by allowing the user to specify one or more columns to sort by, and can also include sorting direction—ascending or descending.

For instance, if a user has a table of employees and wants to see them listed by their last names in alphabetical order, they would use the 'ORDER BY' clause to achieve that. The command enhances the readability and usability of the output by ensuring that the data is arranged in a way that makes sense for analysis or presentation.

In this context, other options describe different functionalities of SQL commands. Retrieving data corresponds to the 'SELECT' command, deleting data relates to the 'DELETE' command, and creating a search index is associated with the 'CREATE INDEX' command. Those commands serve their own unique purposes, but they do not relate to the sorting function provided by 'ORDER BY.'