EXISTS (Transact-SQL)

發行項
09/10/2013

指定測試資料列是否存在的子查詢。

語法

EXISTS subquery

引數

subquery
這是受限制的 SELECT 陳述式。不允許 INTO 關鍵字。如需詳細資訊，請參閱＜SELECT (Transact-SQL)＞中子查詢的相關資訊。

結果類型

Boolean

結果值

如果子查詢包含任何資料列，便傳回 TRUE。

範例

A.在子查詢中使用 NULL，仍會傳回結果集

下列範例在子查詢中指定 NULL 來傳回結果集，使用 EXISTS 仍會評估為 TRUE。

USE AdventureWorks2012 ;
GO
SELECT DepartmentID, Name 
FROM HumanResources.Department 
WHERE EXISTS (SELECT NULL)
ORDER BY Name ASC ;

B.利用 EXISTS 和 IN 來比較查詢

下列範例比較語意相等的兩項查詢。第一項查詢使用 EXISTS，第二項查詢使用 IN。

USE AdventureWorks2012 ;
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

下列查詢使用 IN。

USE AdventureWorks2012 ;
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

以下是任何一項查詢的結果集。

FirstName LastName

-------------------------------------------------- ----------

Barry Johnson

David Johnson

Willis Johnson

(3 row(s) affected)

C.利用 EXISTS 和 = ANY 來比較查詢

下列範例會顯示兩項查詢，它們用來尋找與供應商同名的商店。第一項查詢使用 EXISTS，第二項查詢使用 = ANY。

USE AdventureWorks2012 ;
GO
SELECT DISTINCT s.Name
FROM Sales.Store AS s 
WHERE EXISTS
(SELECT *
    FROM Purchasing.Vendor AS v
    WHERE s.Name = v.Name) ;
GO

下列查詢使用 = ANY。

USE AdventureWorks2012 ;
GO
SELECT DISTINCT s.Name
FROM Sales.Store AS s 
WHERE s.Name = ANY
(SELECT v.Name
    FROM Purchasing.Vendor AS v ) ;
GO

D.利用 EXISTS 和 IN 來比較查詢

下列範例會顯示尋找開頭是 P 之部門員工的查詢。

USE AdventureWorks2012;
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

下列查詢使用 IN。

USE AdventureWorks2012;
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.使用 NOT EXISTS

NOT EXISTS 的作用與 EXISTS 相反。如果子查詢未傳回任何資料列，便滿足 NOT EXISTS 中的 WHERE 子句。下列範例會尋找不在部門中，且名稱開頭是 P 的員工。

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

以下為結果集：

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)

請參閱

參考

運算式 (Transact-SQL)

內建函數 (Transact-SQL)

WHERE (Transact-SQL)

共用方式為