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SQL GROUP BY Statement

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The SQL GROUP BY Statement

The GROUP BY statement groups rows that have the same values into summary rows, like "find the number of customers in each country".

The GROUP BY statement is often used with aggregate functions (COUNT, MAX, MIN, SUM, AVG) to group the result-set by one or more columns.

GROUP BY Syntax

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

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 Constitución 2222 México D.F. 05021 Mexico
3 Antonio Moreno Taquería Antonio Moreno Mataderos 2312 México D.F. 05023 Mexico
4

 Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbköp Christina Berglund Berguvsvägen 8 Luleå S-958 22 Sweden

SQL GROUP BY Examples

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

Example

SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country;
Try it Yourself »

The following SQL statement lists the number of customers in each country, sorted high to low:

Example

SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country
ORDER BY COUNT(CustomerID) DESC;
Try it Yourself »

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 statement lists 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;
Try it Yourself »

Test Yourself With Exercises

Exercise:

List the number of customers in each country.

SELECT (CustomerID),
Country
FROM Customers
;

Start the Exercise


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