PostgreSQL COUNT

COUNT

The COUNT() function returns the number of rows that matches a specified criterion.

If the specified criterion is a column name, the COUNT() function returns the number of rows with that name.

Example

SELECT COUNT(customer_id)
FROM customers;

Note: NULL values are not counted.

By specifying a WHERE clause, you can e.g. return the number of customers that comes from London:

Example

SELECT COUNT(customer_id)
FROM customers
WHERE city = 'London';