Having

💡 Having

Where문에서 집계함수를 사용할 수 없어서 만들어졌다.

집계 함수를 가지고 조건비교를 할 때 사용되며 Group By와 함께 사용된다.

 

Sample Table

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

 

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

 

EmployeeID	LastName	FirstName	BirthDate	Photo	Notes
1	Davolio	Nancy	1968-12-08	EmpID1.pic	Education includes a BA....
2	Fuller	Andrew	1952-02-19	EmpID2.pic	Andrew received his BTS....
3	Leverling	Janet	1963-08-30	EmpID3.pic	Janet has a BS degree....

 

예시

각 국가의 고객 수를 나열하며, 고객이 5명 이상인 국가만 포함한다.

SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country
HAVING COUNT(CustomerId) > 5;

 

위의 예시의 내림차순

SELECT COUNT(CustomerID), Country
FROM Customers
GROUP BY Country
HAVING COUNT(CustomerId) > 5
ORDER BY COUNT(CustomerID) DESC;

 

10개 이상의 주문을 등록한 직원을 반환한다.

SELECT Employees.LastName, COUNT(Orders.OrderID) AS NumberOfOrders
FROM (Orders
INNER JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID)
GROUP BY LastName
HAVING COUNT(Orders.OrderID) > 10;

 

직원 "Davolio" 또는 "Fuller"가 25개 이상의 주문을 등록했는지 여부를 반환한다.

SELECT Employees.LastName, COUNT(Orders.OrderID) AS NumberOfOrders
FROM Orders(
INNER JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID)
WHERE LastName = 'Davolio' OR LastName = 'Fuller'
GROUP BY LastName
HAVING COUNT(Orders.OrderID) > 25;