Creating a complex WHERE clause

I need to get a phone number from a table.  I first want to see if there is a 'Work' number.  If not then look for a 'Business' number.  If not then look for a 'Direct' number.  If not then ' '.

Can I write this using one statement?

Table Phone:
pkPhone
fkContacts
PhoneNo
PhoneType

fkContacts                   PhoneNO                         PhoneType
12155                         (213)555-1212               Direct
12123                         (213)566-3344               Home
12123                         (213)324-3213               Work
12199                          (310)555-1212               Business
huerita37Asked:
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Brian CroweDatabase AdministratorCommented:
WITH ctePhone AS
(
      SELECT pkPhone, fkContacts, PhoneNo, PhoneType,
            P2.Preference,
            ROW_NUMBER() OVER(PARTITION BY fkContacts ORDER BY P2.Preference) AS RowNumber
      FROM Phone AS P
      CROSS APPLY
      (
            SELECT pkPhone,
            CASE PhoneType
                  WHEN 'Work' THEN 1
                  WHEN 'Business' THEN 2
                  WHEN 'Direct' THEN 3
                  ELSE 9
            END AS Preference
            FROM Phone
            WHERE pkPhone = P.pkPhone
      ) AS P2
)
SELECT *
FROM ctePhone
WHERE RowNumber = 1
0

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huerita37Author Commented:
That works perfectly!!!!  Thank you once again for helping me so quickly.  

What is this type of query called?
0
Brian CroweDatabase AdministratorCommented:
The top clause is a common-table expression.  It is equivalent to having a correlated subquery like ...

SELECT ...
FROM ...
WHERE somevalue IN (some other query)

I just find them easier to understand and maintain.  The CROSS APPLY is just used to minimize code reuse otherwise I would have to duplicate the entire CASE statement inside the ROW_NUMBER function.
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