Aggregate Function Combinators

The name of an aggregate function can have a suffix appended to it. This changes the way the aggregate function works.

Distinct

Every unique combination of arguments will be aggregated only once. Repeating values are ignored.

count(distinct(expression))
sum(distinct(expression))
min(distinct(expression))
max(distinct(expression))

Examples

mysql> SELECT sum(distinct(number%3)) FROM numbers_mt(10);
+----------------------------+
| sum(distinct (number % 3)) |
+----------------------------+
|                          3 |
+----------------------------+