COUNT()
This page is part of MariaDB's Documentation.
The parent of this page is: Functions for MariaDB Enterprise Server
Topics on this page:
Overview
Returns the number of values in the given expression.
EXAMPLES
CREATE TABLE t (a INT);
INSERT INTO t VALUES (1), (2), (3);
SELECT COUNT(a) FROM t;
+----------+
| COUNT(a) |
+----------+
| 3 |
+----------+
As Window Function
CREATE TABLE t1 (a INT, b INT);
INSERT INTO t1(a,b) VALUES
(1,3), (1,5), (8,2), (5,7), (5,6),
(10,1), (6,4), (3,9), (3,9), (7,2),
(7,5), (2,6), (9,10), (9,5), (4,8);
SELECT a, COUNT(a) OVER (PARTITION BY b) AS count_a,
AVG(b) OVER (PARTITION BY a) as avg_b
FROM t1
GROUP BY a;
+------+---------+---------+
| a | count_a | avg_b |
+------+---------+---------+
| 1 | 1 | 3.0000 |
| 2 | 1 | 6.0000 |
| 3 | 1 | 9.0000 |
| 4 | 1 | 8.0000 |
| 5 | 1 | 7.0000 |
| 6 | 1 | 4.0000 |
| 7 | 2 | 2.0000 |
| 8 | 2 | 2.0000 |
| 9 | 1 | 10.0000 |
| 10 | 1 | 1.0000 |
+------+---------+---------+
CHANGE HISTORY
EXTERNAL REFERENCES
Additional information on this topic may be found in the MariaDB Public Knowledge Base.