SQL GROUP BY statement

SQL GROUP BY statement

Aggregate functions often need to add GROUP BY statements.

GROUP BY statements are typically used with collection functions (COUNT, MAX, MIN, SUM, AVG) to group the result sets by one or more columns.

GROUP BY statement

The GROUP BY statement is used to group the result set based on one or more columns in conjunction with the Aggregate function.

SQL GROUP BY syntax

SELECT column_name(s)
FROM table_name
WHERE condition
GROUP BY column_name(s)
ORDER BY column_name(s);

Demonstrate the database

In this tutorial, we'll use the well-known Northwind sample database.

Here's the data from the "Customers" table:

SQL GROUP BY example

The following SQL statement lists the number of customers for each country:

SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country;

The following SQL statement lists the number of customers in each country, sorted from highest to thyst:

SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country
ORDER BY COUNT(CustomerID) DESC;

Demonstrate the database

Here's an option for the Order table in the Rosevin sample database:

And select from the Shippers table:

GROUP BY uses the JOIN example

The following SQL statement lists the number of orders sent by each shipper:

SELECT Shippers.ShipperName, COUNT(Orders.OrderID) AS NumberOfOrders FROM Orders
LEFT JOIN Shippers ON Orders.ShipperID = Shippers.ShipperID
GROUP BY ShipperName;