SQL HAVING

SQL HAVING Açıklama

HAVING ifadesi SQL'e eklendi çünkü WHERE anahtar sözcüğü toplama işlevleriyle kullanılamıyor.

SQL HAVING, GROUP BY ifadesi ile oluşturulan gruplara göre değerleri filtrelemek için kullanılır.

HAVING Söz Dizimi

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

Gösteri veritabanı

Aşağıda "Northwind" veritabanının "Customers" ("Müşteriler") tablosundan bir örnek verilmiştir:

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.	5021	Mexico
3	Antonio Moreno Taquería	Antonio Moreno	Mataderos 2312	México D.F.	5023	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 HAVING Örnekler

Aşağıdaki SQL sorgusu her ülkedeki müşteri sayısını listeler. Yalnızca 5'ten fazla müşterisi olan ülkeleri içerir:

Run SQLSELECT COUNT(CustomerID), Country 
FROM Customers 
GROUP BY Country 
HAVING COUNT(CustomerID) > 5

Aşağıdaki SQL sorgusu, her ülkedeki müşteri sayısını en büyükten en küçüğe doğru sıralayarak listeler (yalnızca 5'ten fazla müşterisi olan ülkeleri içerir):

Run SQLSELECT COUNT(CustomerID), Country 
FROM Customers 
GROUP BY Country 
HAVING COUNT(CustomerID) > 5 
ORDER BY COUNT(CustomerID) DESC

Gösteri veritabanı

"Orders" ("Siparişler") tablosundan bir örneğe bakalım:

ProductID	OrderID	CustomerID	EmployeeID	OrderDate	ShipperID
1	10248	90	5	1996-07-04	3
2	10249	81	6	1996-07-05	1
3	10250	34	4	1996-07-08	2
4	10251	84	3	1996-07-08	1
5	10252	76	4	1996-07-09	2

Ve "Employees" ("Çalışanlar") tablosundaki örnek:

EmployeeID	LastName	FirstName	BirthDate	Photo	Notes
1	Davolio	Nancy	12/8/1968	EmpID1.pic	Education includes a BA in psychology from Colorado State University. She also completed (The Art of the Cold Call). Nancy is a member of 'Toastmasters International'.
2	Fuller	Andrew	2/19/1952	EmpID2.pic	Andrew received his BTS commercial and a Ph.D. in international marketing from the University of Dallas. He is fluent in French and Italian and reads German. He joined the company as a sales representative, was promoted to sales manager and was then named vice president of sales. Andrew is a member of the Sales Management Roundtable, the Seattle Chamber of Commerce, and the Pacific Rim Importers Association.
3	Leverling	Janet	8/30/1963	EmpID3.pic	Janet has a BS degree in chemistry from Boston College). She has also completed a certificate program in food retailing management. Janet was hired as a sales associate and was promoted to sales representative.
4	Peacock	Margaret	9/19/1958	EmpID4.pic	Margaret holds a BA in English literature from Concordia College and an MA from the American Institute of Culinary Arts. She was temporarily assigned to the London office before returning to her permanent post in Seattle.
5	Buchanan	Steven	3/4/1955	EmpID5.pic	Steven Buchanan graduated from St. Andrews University, Scotland, with a BSC degree. Upon joining the company as a sales representative, he spent 6 months in an orientation program at the Seattle office and then returned to his permanent post in London, where he was promoted to sales manager. Mr. Buchanan has completed the courses 'Successful Telemarketing' and 'International Sales Management'. He is fluent in French.

Daha Fazla HAVING Örnek

Aşağıdaki SQL sorgusu, 10'dan fazla sipariş kaydeden çalışanları listeler:

Run SQLSELECT 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

Aşağıdaki SQL ifadesi, "Davolio" veya "Fuller" çalışanlarının 25'ten fazla sipariş kaydetmesi durumunda verileri görüntüler:

Run SQLSELECT 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