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count

The count() function retrieves the number of records that match a specific condition. It works with any data type supported by Redpanda SQL and returns a bigint.

The output will indicate the total number of rows in a table, regardless of the input types.

Examples

This example uses an orders table that stores details of the purchase transactions:

CREATE TABLE orders (
    orderid int,
    custname text,
    orderproduct text,
    ordertotal real
);
INSERT INTO orders (orderid, custname, orderproduct, ordertotal)
VALUES
(9557411, 'Maya', 'Jeans', 10.5),
(9557421, 'Aaron', 'T-Shirt', 9.2),
(9557451, 'Alex', 'Hat', 10.8),
(9557311, 'Will', 'Hat', 8.5),
(9557321, 'Will', 'T-Shirt', 12.15),
(9557351, 'Maya', 'T-Shirt', 9.5),
(9557221, 'Maya', 'Jeans', 11.02),
(9557251, 'Alex', 'Jeans', 11.09),
(9557231, 'Aaron', 'Hat', 14.56),
(9557281, 'Aaron', 'Hat', 12.15),
(9557291, 'Will', 'T-Shirt', 13.1);
SELECT * FROM orders;

This query shows the following table:

+----------+-----------+---------------+-------------+
| orderid  | custname  | orderproduct  | ordertotal  |
+----------+-----------+---------------+-------------+
| 9557411  | Maya      | Jeans         | 10.5        |
| 9557421  | Aaron     | T-Shirt       | 9.2         |
| 9557451  | Alex      | Hat           | 10.8        |
| 9557311  | Will      | Hat           | 8.5         |
| 9557321  | Will      | T-Shirt       | 12.15       |
| 9557351  | Maya      | T-Shirt       | 9.5         |
| 9557221  | Maya      | Jeans         | 11.02       |
| 9557251  | Alex      | Jeans         | 11.09       |
| 9557231  | Aaron     | Hat           | 14.56       |
| 9557281  | Aaron     | Hat           | 12.15       |
| 9557291  | Will      | T-Shirt       | 13.1        |
+----------+-----------+---------------+-------------+

count() with a single expression

This example returns the number of all orders in the orders table:

SELECT COUNT(*) FROM orders;

The query returns:

+-------+
| count |
+-------+
| 11    |
+-------+

count() with a GROUP BY clause

This example will combine the count() function and the GROUP BY clause.

  • The GROUP BY clause groups the orders based on the customer’s name.

  • The count() function counts the orders for each customer.

SELECT custname, COUNT (orderid)
FROM orders
GROUP BY custname;

The query returns:

+-----------+--------+
| custname  | count  |
+-----------+--------+
| Aaron     | 3      |
| Alex      | 2      |
| Will      | 3      |
| Maya      | 3      |
+-----------+--------+

count() with a HAVING clause

This example combines the count() function and the HAVING clause to apply a specific condition to find customers who have made more than two orders:

SELECT custname, COUNT (orderid)
FROM orders
GROUP BY custname
HAVING COUNT (orderid) > 2;

  • The GROUP BY clause groups the orders based on the customer’s name.

  • The HAVING clause will filter only customers with more than two order IDs.

  • The count() function counts the orders for each customer.

+-----------+-------+
| custname  | count |
+-----------+-------+
| Aaron     | 3     |
| Will      | 3     |
| Maya      | 3     |
+-----------+-------+