Nested Ordering

If you list more than one column in the ORDER BY clause, your query is ordered by a nested sort. The first level of sort is based on the first column; the second column determines the second level of sort. The following example of a nested sort selects all the rows in the cust_calls table and orders them by call_code and by call_dtime within call_code:

SELECT * FROM cust_calls ORDER BY call_code, call_dtime;