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The SQL GROUP BY Statement

The GROUP BY statement is used to group rows that have the same values into summary rows, like "Find the number of customers in each country".

The GROUP BY statement is almost always used in conjunction with aggregate functions, like COUNT() , MAX() , MIN() , SUM() , AVG() , to perform calculations on each group.

GROUP BY Syntax

SELECT
column1, aggregate_function(column2), column3, ...
FROM
table_name
WHERE
condition
GROUP BY
column1
,
column3
ORDER BY
column_name
;

Demo Database

Below is a selection from the "Customers" table in the Northwind sample database:

CustomerID	CustomerName	ContactName	Address	City	PostalCode	Country
1	Alfreds Futterkiste	Maria Anders	Obere Str. 57	Berlin	12209	Germany
2	Ana Trujillo Emparedados y helados	Ana Trujillo	Avda. de la ConstituciÃ³n 2222	MÃ©xico D.F.	05021	Mexico
3	Antonio Moreno TaquerÃa	Antonio Moreno	Mataderos 2312	MÃ©xico D.F.	05023	Mexico
4	Around the Horn	Thomas Hardy	120 Hanover Sq.	London	WA1 1DP	UK
5	Berglunds snabbkÃ¶p	Christina Berglund	BerguvsvÃ¤gen 8	LuleÃ¥	S-958 22	Sweden

Demo Database

Below is a selection from the "Orders" table in the Northwind sample database:

OrderID	CustomerID	EmployeeID	OrderDate	ShipperID
10248	90	5	1996-07-04	3
10249	81	6	1996-07-05	1
10250	34	4	1996-07-08	2

And a selection from the "Shippers" table:

ShipperID	ShipperName
1	Speedy Express
2	United Package
3	Federal Shipping

GROUP BY With JOIN Example

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

Example

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

  GROUP BY ShipperName;