Most of the time I can get what I want out of SQL using the standard aggregate functions, but today I needed to find the latest timestamp from any one of three columns.
I achieved this using the GREATEST() function, it’s not party of the SQL standard but is commonly available.
GREATEST(value [, …])
LEAST(value [, ...])
The GREATEST and LEAST functions select the largest or smallest value from a list of any number of expressions.