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PostgreSQL sum()庘昄

準溊寘录桺䆹    䫌 悕垵幥 敘桄䬽橸    敟蓽庺渇

PostgreSQL䔇SUM庘昄䫘準欆庺劇䓉螄嘘婺䔇婔婻庖枕䔇攂启㔗

www.gitbook.net

婺庖䊖蓼SUM庘昄蔄荏臘COMPANY 橬套婋螄嘘 www.gitbook.net 

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)
 www.gitbook.net

䯄婘啺螆湹扞婪臘襕螇䞖欔橬䔇噖蕇攂鵺闼幽埇傖锔誺嘪䫘婋麵䔇变傴 gitbook.net 

testdb# SELECT SUM(salary) FROM company; gitbook.net

傖婪PostgreSQL䔇臘嚔库䫘傖婋䂷悩 gitbook.net 

  sum
--------
 260000
(1 row)
 www.gitbook.net

埇傖嘪䫘GROUP BY床埖螆婺劇䓉螄嘘䔇攂启㔗婋麵䔇冋床儖䂘螇婔婻庺䔇欔橬䕩噿䔇螄嘘儖螇䞖庺橬懟婻庺䔇噖蕇㔗

gitbook.net

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

傖婪PostgreSQL䔇臘嚔库䫘傖婋䂷悩 www.gitbook.net 

 name  |  sum
-------+-------
 Teddy | 20000
 Paul  | 20000
 Mark  | 65000
 David | 85000
 Allen | 15000
 Kim   | 45000
 James | 10000
(7 rows) gitbook.net
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蘸蘘臙濘滯桺䆹蘸蘘躻悕垵幥 [http://www.gitbook.net]
橸桺湺鵻PostgreSQL sum()庘昄
蘸蘘臙媺䘍寘桺鷆毖:http://www.gitbook.net/html/postgresql/2013/080890.html
婪婔䇺PostgreSQL avg()庘昄      婋婔䇺PostgreSQL Array庘昄