sum

Description

Returns the sum of non-null values for expr. You can use the DISTINCT keyword to compute the sum of distinct non-null values.

Syntax

SUM([DISTINCT] expr)

Parameters

expr: the expression that evaluates to a numeric value. Supported data types are TINYINT, SMALLINT, INT, FLOAT, DOUBLE, or DECIMAL.

Return value

Data type mapping between input value and return value:

• TINYINT -> BIGINT
• SMALLINT -> BIGINT
• INT -> BIGINT
• FLOAT -> DOUBLE
• DOUBLE -> DOUBLE
• DECIMAL -> DECIMAL

Usage notes

• This function ignores nulls.
• An error is returned if expr does not exist.
• If a VARCHAR expression is passed, this function implicitly casts the input into DOUBLE values. If the cast fails, an error is returned.

Examples

1. Create a table named employees.

   CREATE TABLE IF NOT EXISTS employees (
       region_num    TINYINT        COMMENT "range [-128, 127]",
       id            BIGINT         COMMENT "range [-2^63 + 1 ~ 2^63 - 1]",
       hobby         STRING         NOT NULL COMMENT "upper limit value 65533 bytes",
       income        DOUBLE         COMMENT "8 bytes",
       sales       DECIMAL(12,4)  COMMENT ""
       )
       DISTRIBUTED BY HASH(region_num);

2. Insert data into employees.

   INSERT INTO employees VALUES
   (3,432175,'3',25600,1250.23),
   (4,567832,'3',37932,2564.33),
   (3,777326,'2',null,1932.99),
   (5,342611,'6',43727,45235.1),
   (2,403882,'4',36789,52872.4);

3. Query data from employees.

   MySQL > select * from employees;
   +------------+--------+-------+--------+------------+
   | region_num | id     | hobby | income | sales      |
   +------------+--------+-------+--------+------------+
   |          5 | 342611 | 6     |  43727 | 45235.1000 |
   |          2 | 403882 | 4     |  36789 | 52872.4000 |
   |          4 | 567832 | 3     |  37932 |  2564.3300 |
   |          3 | 432175 | 3     |  25600 |  1250.2300 |
   |          3 | 777326 | 2     |   NULL |  1932.9900 |
   +------------+--------+-------+--------+------------+
   5 rows in set (0.01 sec)

4. Use this function to compute sum.

   Example 1: Calculate the total sales of each region.

   MySQL > SELECT region_num, sum(sales) from employees
   group by region_num;
   
   +------------+------------+
   | region_num | sum(sales) |
   +------------+------------+
   |          2 | 52872.4000 |
   |          5 | 45235.1000 |
   |          4 |  2564.3300 |
   |          3 |  3183.2200 |
   +------------+------------+
   4 rows in set (0.01 sec)

   Example 2: Calculate the total employee income of each region. This function ignores nulls and the income of employee id 777326 is not counted.

   MySQL > select region_num, sum(income) from employees
   group by region_num;
   
   +------------+-------------+
   | region_num | sum(income) |
   +------------+-------------+
   |          2 |       36789 |
   |          5 |       43727 |
   |          4 |       37932 |
   |          3 |       25600 |
   +------------+-------------+
   4 rows in set (0.01 sec)

   Example 3: Calculate the total number of hobbies. The hobby column is of the STRING type and will be implicitly converted to DOUBLE during computation.

   MySQL > select sum(DISTINCT hobby) from employees;
   
   +---------------------+
   | sum(DISTINCT hobby) |
   +---------------------+
   |                  15 |
   +---------------------+
   1 row in set (0.01 sec)

   Example 4: Use sum with the WHERE clause to calculate the total income of employees whose monthly income is higher than 30000.

   MySQL > select sum(income) from employees
   WHERE income > 30000;
   
   +-------------+
   | sum(income) |
   +-------------+
   |      118448 |
   +-------------+
   1 row in set (0.00 sec)

keyword

SUM, sum