SQL Server SUM() Function By Practical Examples

Summary: in this tutorial, you will learn how to use SQL Server SUM() function to calculate the sum of values.

The SQL Server SUM() function is an aggregate function that calculates the sum of all or distinct values in an expression.

The syntax of the SUM() function is as follows:

SUM([ALL | DISTINCT ] expression)
Code language:
 
SQL (Structured Query Language)
 
(
sql





)

In this syntax:

• ALL instructs the SUM() function to return the sum of all values including duplicates. ALL is used by default.
• DISTINCT instructs the SUM() function to calculate the sum of the only distinct values.
•  expression is any valid expression that returns an exact or approximate numeric value. Note that aggregate functions or subqueries are not accepted in the expression.

The SUM() function ignores NULL values.

ALL vs. DISTINCT

Let’s create a new table for demonstration the difference between ALL and DISTINCT:

CREATE
 
TABLE
 t(
    val 
INT
);

INSERT
 
INTO
 t(val)
VALUES
(
1
),(
2
),(
3
),(
3
),(
4
),(
NULL
),(
5
);

SELECT
    val
FROM
    t;
Code language:
 
SQL (Structured Query Language)
 
(
sql
)

The following statement returns the sum of all values in the val column:

SELECT

    
SUM
(val) total
FROM
    t;
Code language:
 
SQL (Structured Query Language)
 
(
sql
)

The output is:

total
-----------
18

Warning: 
Null
 value is eliminated by an aggregate 
or
 other SET operation.

(
1
 row affected)
Code language:
 
PHP
 
(
php
)

However, when we use the DISTINCT modifier, the SUM() function returns the sum of only unique values in the val column:

SELECT

    
SUM
(
DISTINCT
 val) total
FROM
    t;
Code language:
 
SQL (Structured Query Language)
 
(
sql
)

Here is the output:

total
-----------
15

Warning: 
Null
 value is eliminated by an aggregate 
or
 other SET operation.

(
1
 row affected)
Code language:
 
PHP
 
(
php
)

SQL Server SUM() function examples

Let’s take some practical examples of using the SUM() function.

A) Simple SQL Server SUM() function example

The following statement returns the total stocks of all products in all stores:

SELECT
 
    
SUM
(quantity) total_stocks
FROM
 
    production.stocks;
Code language:
 
SQL (Structured Query Language)
 
(
sql
)

The following shows the output:

total_stocks
------------
13511

(1 row affected)

B) SQL Server SUM() function with GROUP BY example

The following statement finds total stocks by store id:

SELECT

    store_id,
    
SUM
(quantity) store_stocks
FROM
    production.stocks
GROUP
 
BY
    store_id;
Code language:
 
SQL (Structured Query Language)
 
(
sql
)

Here is the output:

In this example:

• First, the GROUP BY clause divided the stocks by store id into groups.
• Second, the SUM() function is applied to each group to calculate the total stocks for each.

If you want to display the store name instead of store id, you can use the following statement:

SELECT

    store_name,
    
SUM
(quantity) store_stocks
FROM
    production.stocks w
    
INNER
 
JOIN
 sales.stores s
        
ON
 s.store_id = w.store_id
GROUP
 
BY
    store_name;
Code language:
 
SQL (Structured Query Language)
 
(
sql
)

The following picture shows the output:

C) SQL Server SUM() function with HAVING clause example

The following statement finds stocks for each product and returns only products whose stocks are greater than 100:

SELECT

    product_name,
    
SUM
(quantity) total_stocks
FROM
    production.stocks s
    
INNER
 
JOIN
 production.products p
        
ON
 p.product_id = s.product_id
GROUP
 
BY
    product_name
HAVING
    
SUM
(quantity) > 
100
ORDER
 
BY
    total_stocks 
DESC
;
Code language:
 
SQL (Structured Query Language)
 
(
sql
)

Here is the output:

D) SQL Server SUM() function with expression example

The following example uses an expression in the SUM() function to calculate the net value for each sales order:

SELECT

    order_id,
    
SUM
(
        quantity * list_price * (
1
 - discount)
    ) net_value
FROM
    sales.order_items
GROUP
 
BY
    order_id
ORDER
 
BY
    net_value 
DESC
;
Code language:
 
SQL (Structured Query Language)
 
(
sql
)

The output is as follows:

In this tutorial, you have learned how to use the SQL Server SUM() function to calculate the sum of values.