PostgreSQL COUNT Function

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 columns with that name.

Example

Return the number of customers from the customers table:

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

Return the number of customers from London:

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

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PostgreSQL Exercises

Test Yourself With Exercises

Exercise:

Use the correct function to return the number of records in the customers table with the column name customer_id:SELECT (customer_id) FROM customers;