PostgreSQL - AVG Function

 PostgreSQL AVG function is used to find out the average of a field in various records.

To understand the AVG 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 average of all the SALARY, then you can do so by using the following command −

testdb=# SELECT AVG(SALARY) FROM COMPANY;

The above given PostgreSQL statement will produce the following result −

        avg
 ------------------
  37142.8571428571
(1 row)

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

testdb=# SELECT name, AVG(SALARY) FROM COMPANY GROUP BY name;
  name  |  avg
 -------+-------
  Teddy | 20000
  Paul  | 20000
  Mark  | 65000
  David | 85000
  Allen | 15000
  Kim   | 45000
  James | 10000
(7 rows)

Comments

Post a Comment

Popular posts from this blog

LINUX Move and copy files using SSH

Often you will need to move one or more files/folders or copy them to a different location. You can do so easily using an SSH connection. The commands which you would need to use are mv (short from move) and cp (short from copy). The mv command syntax looks like this: mv configuration.php-dist configuration.php By issuing the above command we will move (rename) the file configuration.php-dist to configuration.php. You can also use mv to move a whole directory and its content: mv includes/* ./ This will move all files (and folders) in the includes/ directory to the current working directory. In some cases however, we will need to only update the files and move only files that were changed, which we can do by passing ‘ -u ’ as argument to the command: mv -u includes/* admin/includes The copy (cp) command works the same way as mv, but instead of moving the files/folders it copies them. For example: cp configuration.php-dist configuration.php The command will copy the co
Read more

PHP Predefined Variables

PHP provides a large number of predefined variables to any script which it runs.PHP provides an additional set of predefined arrays containing variables from the web server the environment, and user input. These new arrays are called superglobals: All the following variables are automatically available in every scope. PHP Superglobals: Variable Description $GLOBALS Contains a reference to every variable which is currently available within the global scope of the script. The keys of this array are the names of the global variables. $_SERVER This is an array containing information such as headers, paths, and script locations. The entries in this array are created by the web server. There is no guarantee that every web server will provide any of these. See next section for a complete list of all the SERVER variables. $_GET An associative array of variables passed to the current script via the HTTP GET method. $_POST An associative array of variable
Read more

Java : Variables Declaring

[1]. Java Variables Variables are containers for storing data values. In Java, there are different types of variables, for example: String - stores text, such as "Hello". String values are surrounded by double quotes int - stores integers (whole numbers), without decimals, such as 123 or -123 float - stores floating point numbers, with decimals, such as 19.99 or -19.99 char - stores single characters, such as 'a' or 'B'. Char values are surrounded by single quotes boolean - stores values with two states: true or false [2]. Declaring (Creating) Variables To create a variable, you must specify the type and assign it a value: Syntax type variable = value ; Where type is one of Java's types (such as int or String), and variable is the name of the variable (such as x or name). The equal sign is used to assign values to the variable. To create a variable that should store text, look at the following example: Example Create a variable called  name  of type  Stri
Read more