W3Schools SQL | #26 SQL GROUP BY STATEMENT

SQL GROUP BY Statement

The SQL GROUP BY Statement

그룹 짓는 함수
주로 aggregate function과 함께 사용된다.
COUNT(), MAX(), MIN(), SUM(), AVG() 등등

GROUP BY Syntax

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

SQL GROUP BY Examples

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

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

GROUP BY With JOIN Example

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