mysql GROUP BY

http://www.w3schools.com/sql/sql_groupby.asp

We use the following SQL statement:

SELECT Customer,SUM(OrderPrice) FROM Orders
GROUP BY Customer

The result-set will look like this:

Customer	SUM(OrderPrice)
Hansen	2000
Nilsen	1700
Jensen	2000

Nice! Isn't it? :)

Let's see what happens if we omit the GROUP BY statement:

SELECT Customer,SUM(OrderPrice) FROM Orders

The result-set will look like this:

Customer	SUM(OrderPrice)
Hansen	5700
Nilsen	5700
Hansen	5700
Hansen	5700
Jensen	5700
Nilsen	5700

The result-set above is not what we wanted.

2
http://www.tizag.com/mysqlTutorial/mysqlgroupby.php

$query = "SELECT type, MIN(price) FROM products GROUP BY type"; 

Display:

Clothing - $32.50
Food - $8.73
Music - $3.99
Toy - $3.99