Топ-100
 

COUNT DISTINCT

RDBMS Type: MySQL
Topic

Syntax:
COUNT(DISTINCT expr,[expr...])

Returns a count of the number of rows with different non-NULL expr
values.

If there are no matching rows, COUNT(DISTINCT) returns 0.

URL: https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html

Example

mysql> SELECT COUNT(DISTINCT results) FROM student;