How do I limit a LEFT JOIN to the 1st result in SQL Server?

Question

I have a bit of SQL that is almost doing what I want it to do. I'm working with three tables, a Users, UserPhoneNumbers and UserPhoneNumberTypes. I'm trying to get a list of users with their phone numbers for an export.

The database itself is old and has some integrity issues. My issue is that there should only ever be 1 type of each phone number in the database but thats not the case. When I run this I get multi-line results for each person if they contain, for example, two "Home" numbers.

How can I modify the SQL to take the first phone number listed and ignore the remaining numbers? I'm in SQL Server and I know about the TOP statement. But if I add 'TOP 1' to the LEFT JOIN select statement its just giving me the 1st entry in the database, not the 1st entry for each User.

This is for SQL Server 2000.

Thanks,

SELECT  Users.UserID, 
  Users.FirstName, Users.LastName,
  HomePhone, WorkPhone, FaxNumber

FROM Users

LEFT JOIN
 (SELECT UserID, PhoneNumber AS HomePhone
 FROM UserPhoneNumbers LEFT JOIN UserPhoneNumberTypes ON UserPhoneNumbers.UserPhoneNumberTypeID=UserPhoneNumberTypes.UserPhoneNumberTypeID
 WHERE UserPhoneNumberTypes.PhoneNumberType='Home') AS tmpHomePhone
 ON tmpHomePhone.UserID = Users.UserID
LEFT JOIN
 (SELECT UserID, PhoneNumber AS WorkPhone
 FROM UserPhoneNumbers LEFT JOIN UserPhoneNumberTypes ON UserPhoneNumbers.UserPhoneNumberTypeID=UserPhoneNumberTypes.UserPhoneNumberTypeID
 WHERE UserPhoneNumberTypes.PhoneNumberType='Work') AS tmpWorkPhone
 ON tmpWorkPhone.UserID = Users.UserID
LEFT JOIN
 (SELECT UserID, PhoneNumber AS FaxNumber
 FROM UserPhoneNumbers LEFT JOIN UserPhoneNumberTypes ON UserPhoneNumbers.UserPhoneNumberTypeID=UserPhoneNumberTypes.UserPhoneNumberTypeID
 WHERE UserPhoneNumberTypes.PhoneNumberType='Fax') AS tmpFaxNumber
 ON tmpFaxNumber.UserID = Users.UserID

Answer 1

Assuming SQL Server 2005+, use ROW_NUMBER:

LEFT JOIN (SELECT UserID, 
                  PhoneNumber AS HomePhone,
                  ROW_NUMBER() OVER (PARTITION BY userid ORDER BY what?) AS rank
             FROM UserPhoneNumbers  upn
        LEFT JOIN UserPhoneNumberTypes upnt ON upnt.UserPhoneNumberTypeID = upn.UserPhoneNumberTypeID
                                           AND upnt.PhoneNumberType='Home') AS tmpHomePhone
                ON tmpHomePhone.UserID = Users.UserID
               AND tmpHomePhone.rank = 1

Mind the what? placeholder for determining the first number. Omit the ORDER BY if you don't care at all...