GREATEST and LEAST functions - Amazon Redshift
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GREATEST and LEAST functions

Returns the largest or smallest value from a list of any number of expressions.


GREATEST (value [, ...]) LEAST (value [, ...])



A comma-separated list of expressions, such as column names. The expressions must all be convertible to a common data type. NULL values in the list are ignored. If all of the expressions evaluate to NULL, the result is NULL.


Returns the greatest (for GREATEST) or least (for LEAST) value from the provided list of expressions.


The following example returns the highest value alphabetically for firstname or lastname.

select firstname, lastname, greatest(firstname,lastname) from users where userid < 10 order by 3; firstname | lastname | greatest -----------+-----------+----------- Lars | Ratliff | Ratliff Reagan | Hodge | Reagan Colton | Roy | Roy Barry | Roy | Roy Tamekah | Juarez | Tamekah Rafael | Taylor | Taylor Victor | Hernandez | Victor Vladimir | Humphrey | Vladimir Mufutau | Watkins | Watkins (9 rows)