Table-Valued User-Defined Functions

http://technet.microsoft.com/en-us/library/ms191165.aspx

USE AdventureWorks2008R2;
GO
IF OBJECT_ID(N'dbo.ufnGetContactInformation', N'TF') IS NOT NULL
    DROP FUNCTION dbo.ufnGetContactInformation;
GO
CREATE FUNCTION dbo.ufnGetContactInformation(@ContactID int)
RETURNS @retContactInformation TABLE 
(
    -- Columns returned by the function
    ContactID int PRIMARY KEY NOT NULL, 
    FirstName nvarchar(50) NULL, 
    LastName nvarchar(50) NULL, 
    JobTitle nvarchar(50) NULL, 
    ContactType nvarchar(50) NULL
)
AS 
-- Returns the first name, last name, job title, and contact type for the specified contact.
BEGIN
    DECLARE 
        @FirstName nvarchar(50), 
        @LastName nvarchar(50), 
        @JobTitle nvarchar(50), 
        @ContactType nvarchar(50);
    -- Get common contact information
    SELECT 
        @ContactID = BusinessEntityID, 
        @FirstName = FirstName, 
        @LastName = LastName
    FROM Person.Person 
    WHERE BusinessEntityID = @ContactID;
    -- Get contact job title
    SELECT @JobTitle = 
        CASE 
            -- Check for employee
            WHEN EXISTS(SELECT * FROM Person.Person AS p 
                        WHERE p.BusinessEntityID = @ContactID AND p.PersonType = 'EM') 
                THEN (SELECT JobTitle 
                      FROM HumanResources.Employee AS e
                      WHERE e.BusinessEntityID = @ContactID)
            -- Check for vendor
            WHEN EXISTS(SELECT * FROM Person.Person AS p 
                        WHERE p.BusinessEntityID = @ContactID AND p.PersonType = 'VC') 
                THEN (SELECT ct.Name 
                      FROM Person.ContactType AS ct 
                      INNER JOIN Person.BusinessEntityContact AS bec 
                          ON bec.ContactTypeID = ct.ContactTypeID  
                      WHERE bec.PersonID = @ContactID)
                    
            -- Check for store
            WHEN EXISTS(SELECT * FROM Person.Person AS p 
                        WHERE p.BusinessEntityID = @ContactID AND p.PersonType = 'SC') 
                THEN (SELECT ct.Name 
                      FROM Person.ContactType AS ct 
                      INNER JOIN Person.BusinessEntityContact AS bec 
                          ON bec.ContactTypeID = ct.ContactTypeID  
                      WHERE bec.PersonID = @ContactID)
            ELSE NULL 
        END;
    -- Get contact type
    SET @ContactType = 
        CASE 
            -- Check for employee
            WHEN EXISTS(SELECT * FROM Person.Person AS p 
                        WHERE p.BusinessEntityID = @ContactID AND p.PersonType = 'EM') 
            THEN 'Employee'
            -- Check for vendor
            WHEN EXISTS(SELECT * FROM Person.Person AS p 
                        WHERE p.BusinessEntityID = @ContactID AND p.PersonType = 'VC')
            THEN 'Vendor Contact'
            -- Check for store
            WHEN EXISTS(SELECT * FROM Person.Person AS p 
                        WHERE p.BusinessEntityID = @ContactID AND p.PersonType = 'SC')
            THEN 'Store Contact'
            -- Check for individual consumer
            WHEN EXISTS(SELECT * FROM Person.Person AS p 
                        WHERE p.BusinessEntityID = @ContactID AND p.PersonType = 'IN') 
            THEN 'Consumer'
             -- Check for general contact
            WHEN EXISTS(SELECT * FROM Person.Person AS p 
                        WHERE p.BusinessEntityID = @ContactID AND p.PersonType = 'GC') 
            THEN 'General Contact'
        END;
    -- Return the information to the caller
    IF @ContactID IS NOT NULL 
    BEGIN
        INSERT @retContactInformation
        SELECT @ContactID, @FirstName, @LastName, @JobTitle, @ContactType;
    END;
    RETURN;
END;
GO