PostgreSQL 18 reference · Aggregate Functions

PostgreSQL COUNT() Function

Count rows: count(*) counts every row, count(x) skips NULLs, and count(DISTINCT x) counts unique values. Returns bigint.

PostgreSQL 18

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Syntax

count(*)  |  count(expression)  |  count(DISTINCT expression)

Parameter	Description
`expression`	A column or expression.

bigint (0 for no rows).

Three kinds of count

SELECT count(*) AS customers, count(email) AS with_email, count(DISTINCT country) AS countries
FROM customers;

Output

 customers | with_email | countries
-----------+------------+-----------
        10 |          9 |         5
(1 row)

Run this on your computer — see “Get Started” for setup.

Per group

SELECT status, count(*) AS orders
FROM orders
GROUP BY status
ORDER BY orders DESC, status;

Output

  status   | orders
-----------+--------
 delivered |      7
 pending   |      2
 shipped   |      2
 cancelled |      1
(4 rows)

Run this on your computer — see “Get Started” for setup.

SUM() · Add up the non-NULL values in a group. Returns NULL, not 0, when there are no rows; wrap it in coalesce() if needed.
FILTER · Restrict which rows one aggregate sees with FILTER (WHERE …), so one query can count several conditions.
SQL Aggregate Functions · tutorial
SQL GROUP BY · tutorial