EXISTS (Transact-SQL)
Satır varlığını sınamak için bir alt sorgu belirtir.
Sözdizimi
EXISTS subquery
Bağımsız değişkenler
- subquery
Kısıtlı bir select deyimolur.compute yan tümce ve INTO anahtar sözcüğü verilmez.Sorgularda hakkında bilgi daha fazla bilgi için bkz: SELECT (Transact-SQL).
Sonuç türleri
Boolean
Sonuç değerleri
alt sorgu ise doğru verir tüm satırları içerir.
Örnekler
A.Hala bir sonuç kümesidöndürmek için bir alt sorgu içinde null kullanarak
Aşağıdaki örnek bir sonuç kümesi ile verir NULL hala kullanarak true değerlendirir ve belirtilen alt sorgu içinde EXISTS.
USE AdventureWorks2008R2 ;
GO
SELECT DepartmentID, Name
FROM HumanResources.Department
WHERE EXISTS (SELECT NULL)
ORDER BY Name ASC ;
B.EXISTS ve ın kullanarak sorguları karşılaştırma
Aşağıdaki örnek gönderilmesinin eşdeğerdir iki sorgu karşılaştırır.İlk sorguyu kullanır EXISTS ve ikinci sorguyu kullanır IN.
USE AdventureWorks2008R2 ;
GO
SELECT a.FirstName, a.LastName
FROM Person.Person AS a
WHERE EXISTS
(SELECT *
FROM HumanResources.Employee AS b
WHERE a.BusinessEntityID = b.BusinessEntityID
AND a.LastName = 'Johnson');
GO
Aşağıdaki sorgu kullanır IN.
USE AdventureWorks2008R2 ;
GO
SELECT a.FirstName, a.LastName
FROM Person.Person AS a
WHERE a.LastName IN
(SELECT a.LastName
FROM HumanResources.Employee AS b
WHERE a.BusinessEntityID = b.BusinessEntityID
AND a.LastName = 'Johnson');
GO
İşte sonuç kümesi için sorgular.
FirstName LastName
-------------------------------------------------- ----------
Barry Johnson
David Johnson
Willis Johnson
(3 row(s) affected)
C.EXISTS kullanarak sorguları karşılaştırma ve = herhangi
Aşağıdaki örnek, aynı adı taşıyan bir satıcı adı olan mağazaları için iki sorgu gösterir.İlk sorguyu kullanır EXISTS ve ikinci =ANY.
USE AdventureWorks2008R2 ;
GO
SELECT DISTINCT s.Name
FROM Sales.Store AS s
WHERE EXISTS
(SELECT *
FROM Purchasing.Vendor AS v
WHERE s.Name = v.Name) ;
GO
Aşağıdaki sorgu kullanır = ANY.
USE AdventureWorks2008R2 ;
GO
SELECT DISTINCT s.Name
FROM Sales.Store AS s
WHERE s.Name = ANY
(SELECT v.Name
FROM Purchasing.Vendor AS v ) ;
GO
D.EXISTS ve ın kullanarak sorguları karşılaştırma
Aşağıdaki örnek ile başlayan departmanların çalışanları bulmak için sorguları gösterir P.
USE AdventureWorks2008R2;
GO
SELECT p.FirstName, p.LastName, e.JobTitle
FROM Person.Person AS p
JOIN HumanResources.Employee AS e
ON e.BusinessEntityID = p.BusinessEntityID
WHERE EXISTS
(SELECT *
FROM HumanResources.Department AS d
JOIN HumanResources.EmployeeDepartmentHistory AS edh
ON d.DepartmentID = edh.DepartmentID
WHERE e.BusinessEntityID = edh.BusinessEntityID
AND d.Name LIKE 'P%');
GO
Aşağıdaki sorgu kullanır IN.
USE AdventureWorks2008R2;
GO
SELECT p.FirstName, p.LastName, e.JobTitle
FROM Person.Person AS p JOIN HumanResources.Employee AS e
ON e.BusinessEntityID = p.BusinessEntityID
JOIN HumanResources.EmployeeDepartmentHistory AS edh
ON e.BusinessEntityID = edh.BusinessEntityID
WHERE edh.DepartmentID IN
(SELECT DepartmentID
FROM HumanResources.Department
WHERE Name LIKE 'P%');
GO
E.not EXISTS kullanma
not EXISTS EXISTS tersini çalışır.alt sorgutarafından döndürülen satır yok, where yan tümce tümcesinde not EXISTS gerçekleşti.Aşağıdaki örnek ile başlayan adları olan departmanları olmayan çalışanlar bulur P.
SELECT p.FirstName, p.LastName, e.JobTitle
FROM Person.Person AS p
JOIN HumanResources.Employee AS e
ON e.BusinessEntityID = p.BusinessEntityID
WHERE NOT EXISTS
(SELECT *
FROM HumanResources.Department AS d
JOIN HumanResources.EmployeeDepartmentHistory AS edh
ON d.DepartmentID = edh.DepartmentID
WHERE e.BusinessEntityID = edh.BusinessEntityID
AND d.Name LIKE 'P%')
ORDER BY LastName, FirstName
GO
Sonuç kümesi buradadır.
FirstName LastName Title
------------------------------ ------------------------------ ------------
Syed Abbas Pacific Sales Manager
Hazem Abolrous Quality Assurance Manager
Humberto Acevedo Application Specialist
Pilar Ackerman Shipping & Receiving Superviso
François Ajenstat Database Administrator
Amy Alberts European Sales Manager
Sean Alexander Quality Assurance Technician
Pamela Ansman-Wolfe Sales Representative
Zainal Arifin Document Control Manager
David Barber Assistant to CFO
Paula Barreto de Mattos Human Resources Manager
Shai Bassli Facilities Manager
Wanida Benshoof Marketing Assistant
Karen Berg Application Specialist
Karen Berge Document Control Assistant
Andreas Berglund Quality Assurance Technician
Matthias Berndt Shipping & Receiving Clerk
Jo Berry Janitor
Jimmy Bischoff Stocker
Michael Blythe Sales Representative
David Bradley Marketing Manager
Kevin Brown Marketing Assistant
David Campbell Sales Representative
Jason Carlson Information Services Manager
Fernando Caro Sales Representative
Sean Chai Document Control Assistant
Sootha Charncherngkha Quality Assurance Technician
Hao Chen HR Administrative Assistant
Kevin Chrisulis Network Administrator
Pat Coleman Janitor
Stephanie Conroy Network Manager
Debra Core Application Specialist
Ovidiu Crãcium Sr. Tool Designer
Grant Culbertson HR Administrative Assistant
Mary Dempsey Marketing Assistant
Thierry D'Hers Tool Designer
Terri Duffy VP Engineering
Susan Eaton Stocker
Terry Eminhizer Marketing Specialist
Gail Erickson Design Engineer
Janice Galvin Tool Designer
Mary Gibson Marketing Specialist
Jossef Goldberg Design Engineer
Sariya Harnpadoungsataya Marketing Specialist
Mark Harrington Quality Assurance Technician
Magnus Hedlund Facilities Assistant
Shu Ito Sales Representative
Stephen Jiang North American Sales Manager
Willis Johnson Recruiter
Brannon Jones Finance Manager
Tengiz Kharatishvili Control Specialist
Christian Kleinerman Maintenance Supervisor
Vamsi Kuppa Shipping & Receiving Clerk
David Liu Accounts Manager
Vidur Luthra Recruiter
Stuart Macrae Janitor
Diane Margheim Research & Development Enginee
Mindy Martin Benefits Specialist
Gigi Matthew Research & Development Enginee
Tete Mensa-Annan Sales Representative
Ramesh Meyyappan Application Specialist
Dylan Miller Research & Development Manager
Linda Mitchell Sales Representative
Barbara Moreland Accountant
Laura Norman Chief Financial Officer
Chris Norred Control Specialist
Jae Pak Sales Representative
Wanda Parks Janitor
Deborah Poe Accounts Receivable Specialist
Kim Ralls Stocker
Tsvi Reiter Sales Representative
Sharon Salavaria Design Engineer
Ken Sanchez Chief Executive Officer
José Saraiva Sales Representative
Mike Seamans Accountant
Ashvini Sharma Network Administrator
Janet Sheperdigian Accounts Payable Specialist
Candy Spoon Accounts Receivable Specialist
Michael Sullivan Sr. Design Engineer
Dragan Tomic Accounts Payable Specialist
Lynn Tsoflias Sales Representative
Rachel Valdez Sales Representative
Garrett Vargar Sales Representative
Ranjit Varkey Chudukatil Sales Representative
Bryan Walton Accounts Receivable Specialist
Jian Shuo Wang Engineering Manager
Brian Welcker VP Sales
Jill Williams Marketing Specialist
Dan Wilson Database Administrator
John Wood Marketing Specialist
Peng Wu Quality Assurance Supervisor
(91 row(s) affected)