EXISTS (Transact-SQL)

行が存在するかどうかをテストするサブクエリを指定します。

Transact-SQL 構文表記規則

構文

EXISTS subquery

引数

• subquery
  制限付きの SELECT ステートメントを指定します。COMPUTE 句、および INTO キーワードは許可されません。詳細については、「SELECT (Transact-SQL)」のサブクエリに関する情報を参照してください。

戻り値の型

Boolean

戻り値

サブクエリが行を含む場合は、TRUE を返します。

例

A. サブクエリで NULL を使用しても結果セットを返すようにする

次の例では、サブクエリに NULL を指定しても、EXISTS により TRUE と評価されるので、結果が返されます。

USE AdventureWorks2008R2 ;
GO
SELECT DepartmentID, Name 
FROM HumanResources.Department 
WHERE EXISTS (SELECT NULL)
ORDER BY Name ASC ;

B. EXISTS と IN を使用してクエリを比較する

次の例では、意味的に等価な 2 つのクエリを比較します。最初のクエリでは EXISTS を使用し、2 番目のクエリでは IN を使用します。

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

次のクエリでは IN を使用します。

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

次に各クエリの結果セットを示します。

FirstName LastName

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

Barry Johnson

David Johnson

Willis Johnson

(3 row(s) affected)

C. EXISTS と = ANY を使用してクエリを比較する

次の例では、ベンダーと同じ名前の店を検索する 2 つのクエリを示します。最初のクエリでは EXISTS を使用し、2 番目のクエリでは =ANY を使用します。

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

次のクエリでは = ANY を使用します。

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 と IN を使用してクエリを比較する

次の例では、P で始まる部署の従業員を検索するクエリを示します。

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

次のクエリでは IN を使用します。

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 を使用する

NOT EXISTS は EXISTS とは逆の動作をします。NOT EXISTS 内の WHERE 句の条件は、サブクエリから行が返されない場合に満たされます。次の例では、P で始まる部署に属していない従業員を検索します。

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

以下に結果セットを示します。

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)

関連項目

参照

式 (Transact-SQL)

組み込み関数 (Transact-SQL)

WHERE (Transact-SQL)