SUM0

Description

Used to return the sum of all values of the selected field. Unlike the SUM function, when all input values are NULL, SUM0 returns 0 instead of NULL.

Syntax

SUM0(<expr>)

Parameters

Parameter	Description
<expr>	The field to calculate the sum of

Return Value

Returns the sum of all values of the selected field. If all values are NULL, returns 0.

Examples

-- Create example table
CREATE TABLE sales_table (
    product_id INT,
    price DECIMAL(10,2),
    quantity INT,
    discount DECIMAL(10,2)
) DISTRIBUTED BY HASH(product_id)
PROPERTIES (
    "replication_num" = "1"
);

-- Insert test data
INSERT INTO sales_table VALUES
(1, 99.99, 2, NULL),
(2, 159.99, 1, NULL),
(3, 49.99, 5, NULL),
(4, 299.99, 1, NULL),
(5, 79.99, 3, NULL);

-- Compare SUM and SUM0
SELECT 
    SUM(discount) as sum_discount,    -- Returns NULL
    SUM0(discount) as sum0_discount   -- Returns 0
FROM sales_table;

+--------------+---------------+
| sum_discount | sum0_discount |
+--------------+---------------+
|         NULL |          0.00 |
+--------------+---------------+