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  PostgreSQL numeric functions are used primarily for numeric manipulation and/or mathematical calculations. The following table details the numeric functions − ABS(X) The ABS() function returns the absolute value of X. Consider the following example − testdb =# SELECT ABS ( 2 ); +---------------------------------------------------------+ | ABS ( 2 ) | +---------------------------------------------------------+ | 2 | +---------------------------------------------------------+ 1 row in set ( 0.00 sec ) testdb =# SELECT ABS (- 2 ); +---------------------------------------------------------+ | ABS ( 2 ) | +---------------------------------------------------------+ | 2 | +---------------------------------------------------------+ 1 row in set ( 0.00 sec )

  PostgreSQL   ARRAY_AGG   function is used to concatenate the input values including null into an array. To understand the  ARRAY_AGG  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 use the ARRAY_AGG, you can do so by using the following command − testdb =# SELECT ARRAY_AGG ( SALARY ) FROM COMPANY ; The above given PostgreSQL statement will produce the following result − array_agg --------------------------------------------- {20000,1

  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