COUNT()

Overview

Returns the number of values in the given expression.

See also: Functions in 10.6 ES, in 10.5 ES, and in 10.4 ES

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

Release Series

History

10.6 Enterprise

  • Present starting in MariaDB Enterprise Server 10.6.4-1.

10.5 Enterprise

  • Present starting in MariaDB Enterprise Server 10.5.3-1.

10.4 Enterprise

  • Present starting in MariaDB Enterprise Server 10.4.6-1.

EXTERNAL REFERENCES