PostgreSQL - SUM Function

 PostgreSQL SUM function is used to find out the sum of a field in various records.

To understand the SUM function consider the table COMPANY having records as follows −

testdb# select * from COMPANY;
 id | name  | age | address   | salary
----+-------+-----+-----------+--------
  1 | Paul  |  32 | California|  20000
  2 | Allen |  25 | Texas     |  15000
  3 | Teddy |  23 | Norway    |  20000
  4 | Mark  |  25 | Rich-Mond |  65000
  5 | David |  27 | Texas     |  85000
  6 | Kim   |  22 | South-Hall|  45000
  7 | James |  24 | Houston   |  10000
(7 rows)

Now, based on the above table, suppose you want to calculate the total of all the salary, then you can do so by using the following command −

testdb# SELECT SUM(salary) FROM company;

The above given PostgreSQL statement will produce the following result −

  sum
--------
 260000
(1 row)

You can take the sum of various records set using the GROUP BY clause. The following example will sum up all the records related to a single person and you will have salary for each person.

testdb# SELECT name, SUM(salary) FROM company GROUP BY name;

The above given PostgreSQL statement will produce the following result −

 name  |  sum
-------+-------
 Teddy | 20000
 Paul  | 20000
 Mark  | 65000
 David | 85000
 Allen | 15000
 Kim   | 45000
 James | 10000
(7 rows)

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