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)
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There are two sides to machine learning:
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- Theoretical Machine Learning: This is about math and abstraction and idealized scenarios and limits and beauty and informing what is possible. It is a whole lot neater and cleaner and removed from the mess of reality.
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