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EXISTS (Transact-SQL)

Especifica uma subconsulta a ser testada quanto à existência de linhas.

Ícone de vínculo de tópicoConvenções de sintaxe Transact-SQL

Sintaxe

EXISTS subquery

Argumentos

  • subquery
    É uma instrução SELECT restrita. A cláusula COMPUTE e a palavra-chave INTO não são permitidas. Para obter mais informações, leia sobre subconsultas em SELECT (Transact-SQL).

Tipos de resultado

Boolean

Valores de resultado

Retornará TRUE se uma subconsulta tiver qualquer linha.

Exemplos

A. Usando NULL em uma subconsulta para ainda a retornar um conjunto de resultados

O exemplo a seguir retorna um conjunto de resultados com NULL especificado na subconsulta e ainda é avaliado como TRUE usando EXISTS.

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

B. Comparando consultas usando EXISTS e IN

O exemplo a seguir compara duas consultas semanticamente equivalentes. A primeira consulta usa EXISTS e a segunda usa IN.

USE AdventureWorks ;
GO
SELECT a.FirstName, a.LastName
FROM Person.Contact AS a
WHERE EXISTS
(SELECT * 
    FROM HumanResources.Employee AS b
    WHERE a.ContactId = b.ContactID
    AND a.LastName = 'Johnson');
GO

A consulta a seguir usa IN.

USE AdventureWorks ;
GO
SELECT a.FirstName, a.LastName
FROM Person.Contact AS a
WHERE a.LastName IN
(SELECT a.LastName
    FROM HumanResources.Employee AS b
    WHERE a.ContactId = b.ContactID
    AND a.LastName = 'Johnson');
GO

Este é o conjunto de resultados para ambas as consultas.

FirstName                                          LastName
-------------------------------------------------- ----------
Barry                                              Johnson
David                                              Johnson
Willis                                             Johnson
(3 row(s) affected)

C. Comparando consultas usando EXISTS e = ANY

O exemplo a seguir mostra duas consultas para localizar lojas cujo nome seja igual ao de um fornecedor. A primeira consulta usa EXISTS e a segunda usa =ANY.

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

A consulta a seguir usa = ANY:

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

D. Comparando consultas usando EXISTS e IN

O exemplo a seguir mostra consultas para localizar os funcionários de departamentos que começam com P.

USE AdventureWorks;
GO
SELECT c.FirstName, c.LastName, e.Title
FROM Person.Contact AS c 
JOIN HumanResources.Employee AS e
   ON e.ContactID = c.ContactID 
WHERE EXISTS
(SELECT *
    FROM HumanResources.Department AS d
    JOIN HumanResources.EmployeeDepartmentHistory AS edh
       ON d.DepartmentID = edh.DepartmentID
    WHERE e.EmployeeID = edh.EmployeeID
    AND d.Name LIKE 'P%');
GO

A consulta a seguir usa IN.

USE AdventureWorks;
GO
SELECT c.FirstName, c.LastName, e.Title
FROM Person.Contact AS c JOIN HumanResources.Employee AS e
   ON e.ContactID = c.ContactID 
JOIN HumanResources.EmployeeDepartmentHistory AS edh
   ON e.EmployeeID = edh.EmployeeID 
WHERE edh.DepartmentID IN
(SELECT DepartmentID
   FROM HumanResources.Department
   WHERE Name LIKE 'P%');
GO

E. Usando NOT EXISTS

NOT EXISTS funciona de forma contrária a EXISTS. A cláusula WHERE em NOT EXISTS será atendida se nenhuma linha for retornada pela subconsulta. O exemplo a seguir localiza funcionários que não estão em departamentos que têm nomes que começam com P.

SELECT c.FirstName, c.LastName, e.Title
FROM Person.Contact AS c 
JOIN HumanResources.Employee AS e
   ON e.ContactID = c.ContactID 
WHERE NOT EXISTS
(SELECT *
   FROM HumanResources.Department AS d
   JOIN HumanResources.EmployeeDepartmentHistory AS edh
      ON d.DepartmentID = edh.DepartmentID
   WHERE e.EmployeeID = edh.EmployeeID
   AND d.Name LIKE 'P%')
ORDER BY LastName, FirstName
GO

Conjunto de resultados.

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)