COALESCE() Function

 Return the first non-null value in a list.

Example:

SELECT COALESCE(NULL, NULL, NULL, 'value 1', NULL, 'value 2') FROM dual;

Output: value 1

Find second max value in the table (nth max value)

--Second maximum column value

SELECT *

FROM customers

ORDER BY age DESC, first_name ASC

LIMIT 1,1; -- 1 - number of row to omit, 1 - no of records to show