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MySQL Aggregate Functions - SUM()

This lesson will teach you how to use the aggregate function SUM(). If you haven't already read through corejava's Aggregate Introduction Lesson, please check it out now. It explains concepts used in this lesson.

We will be using the "products" table again -- this time to display the use of MySQL's SUM function.

You can download the products.sql file from our website. If you are new to MySQL you will need to know how to Create a MySQL Table and Insert a MySQL Row.

Here's a visual of the "products" table.

Products Table:
123451Park's Great HitsMusic19.99
123452Silly PuddyToy3.99
123454Men's T-ShirtClothing32.50
123456Electronica 2002Music3.99
123457Country TunesMusic21.55
MySQL SUM - Totaling Groups

SUM is an aggregate function that totals a specific column for a group. The "products" table that is displayed above has several products of various types. One use of SUM might be to find the total of all the items' price for each product type.

Just as we did in the aggregate introduction lesson, we are going to apply the aggregate function to price and GROUP BY type to create four groups: Music, Toy, Clothing and Food.

PHP and MySQL Code:
	// Make a MySQL Connection

	$query = "SELECT type, SUM(price) FROM products GROUP BY type"; 
	$result = mysql_query($query) or die(mysql_error());

	// Print out result
	while($row = mysql_fetch_array($result)){
		echo "Total ". $row['type']. " = $". $row['SUM(price)'];
		echo "<br />";
	Total Clothing = $67.47
Total Food = $8.73
Total Music = $45.53
Total Toy = $93.94
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