How to find record groups that match other record groups (relational division?)

Question

To set up consolidated account processing, I want to find out accounts that have the “exact same” set of owners.

I think this might work to deploy dynamic sql owners and then use it but I don't want to continue this approach; I do not have an upper limit on the number of names that can be associated with this account, so I want to avoid dynamic SQL.

My details (also this is at http://www.sqlfiddle.com/#!3/1d36e )

 CREATE TABLE allacctRels
 (account INT NOT NULL,
 module CHAR(3) NOT NULL,
 custCode CHAR(20) NOT NULL)


 INSERT INTO allacctrels
 (account, module, custCode)
 VALUES
 (1, 'DDA', 'Wilkie, Walker'),
 (1, 'DDA', 'Houzemeal, Juvy'),
 (2, 'CDS', 'Chase, Billy'),
 (2, 'CDS', 'Norman, Storm'),
 (3, 'CDS', 'Chase, Billy'),
 (3, 'CDS', 'Norman, Storm'),
 (7, 'CDS', 'Perkins, Tony'),
 (15, 'SVG', 'Wilkie, Walker'), --typo in name before mwigdahl response
 (16, 'SVG', 'Wilkie, Walker'), -- corrected typo here too
 (606, 'DDA', 'Norman, Storm'),
 (606, 'DDA', 'Chase, Billy'),-- corrected 2nd typo found 
 (4, 'LNS', 'Wilkie, Walker'),
 (4, 'LNS', 'Houzemeal, Juvy'),
 (44, 'DDA', 'Perkins, Tony'),
 (222, 'DDA', 'Wilkie, Walker'),
 (222, 'DDA', 'Houzemeal, Juvy'),
 (17, 'SVG', 'Wilkie, Walker'), -- added these three rows in edit, SVG 17 doesn't match any dda 
 (17, 'SVG', 'Welch, Raquel'),
 (17, 'SVG', 'Houzemeal, Juvy')

I want to find out, for each MODULE-ACCOUNT, what is the lowest DDA account that the same owners have associated with it.

, DDA, . , -/ - SELECT DISTINCT, FROM allAcctRels)

1, DDA, 1
2, CDS, 606
3, CDS, 606
15, SVG, NULL
16, SVG, NULL
606, DDA, 606
4, LNS, 1
7, CDS, 44
44, DDA, 44
222, DDA, 1
17, SVG, NULL -- added to original post.

SVG 15 16 DDA, , , NULL . EDIT: SVG 17 , SVG 17 DDA acct, , SVG 17 DDA acct. DDA , dda DDA ( DDA 222).

, , , row_number. , , , SQL, .

, " ", , , "" . , dda, , , , , , dda, , "" .

-- this is what I tried but I'm not sure it the logic would work
-- and I can't figure out how to pass the account holders for each
-- account in.  This is a bit changed from the function I wrote, some
    -- extraneous fields removed and cryptic column names changed.  So it 
    -- probably won't run as is.

    -- to support a parameter type to a tape
-- CREATE type VisionCustomer as Table
-- (customer varchar(30))

CREATE FUNCTION  consolidatable 
(@custList dbo.VisionCustomer READONLY)
RETURNS char(10)
AS  
BEGIN
DECLARE @retval Varchar(10)
DECLARE @howmany int
select @howmany=Count(*) FROM @custlist;

SELECT @retval = min (acct) FROM allAcctRels
    JOIN @custlist
        On VendorCustNo = Customer
            WHERE acctType = 'DDA'
            GROUP BY acct
            HAVING (count(*) = @howmany)
            and
            COUNT(*) = (select Count(*) FROM allAcctRels X
    WHERE X.acctType = 'DDA'
    AND X.account = AllAcctRels.account) ;
RETURN @retval
END;

Answer 1

, . :

SELECT a.account, a.module, MIN(b.account) 
FROM allacctRels a
    LEFT JOIN allacctRels b ON a.custCode = b.custCode AND b.module = 'DDA'
GROUP BY a.account, a.module

: , . . , , .

SELECT a.account, a.module, MIN(b.account)
FROM allacctRels a
    LEFT JOIN allacctRels b ON b.module = 'DDA'
    AND
    -- first test is to confirm that the number of matching names for this combination equals the number of names for the DDA set...
    (
        SELECT COUNT(*) 
        FROM allacctRels b2 
            INNER JOIN allacctRels a2 ON b2.custCode = a2.custCode 
        WHERE a.account = a2.account AND b.account = b2.account
    ) = 
    (
        SELECT COUNT(*) 
        FROM allacctRels b2 
        WHERE b.account = b2.account
    )
    AND 
    -- second test is to confirm that the number of names for the DDA set equals the number of names for the base set...
    (
        SELECT COUNT(*) 
        FROM allacctRels b2 
        WHERE b.account = b2.account
    ) = 
    (
        SELECT COUNT(*) 
        FROM allacctRels a2 
        WHERE a.account = a2.account
    )
GROUP BY a.account, a.module

Answer 2

, , (http://www.sqlfiddle.com/#!3/f96c5/1):

;WITH AccountsWithOwners AS
(
  SELECT DISTINCT
    DA.module
    , DA.account
    , STUFF((SELECT 
                 ',' + AAR.custCode
               FROM allacctRels AAR 
               WHERE AAR.module = DA.module 
                 AND AAR.account = DA.account
               ORDER BY AAR.custCode
               FOR XML PATH(''))
              , 1, 1, '') AS Result
  FROM allacctRels DA
) 
, WithLowestDda AS
(
    SELECT
        AWO.module
        , AWO.account
        , MatchingAccounts.account AS DdaAccount
        , ROW_NUMBER() OVER(PARTITION BY AWO.module, AWO.account ORDER BY MatchingAccounts.account) AS Row
    FROM AccountsWithOwners AWO
    LEFT JOIN AccountsWithOwners MatchingAccounts
        ON MatchingAccounts.module = 'DDA'
        AND MatchingAccounts.Result = AWO.Result
)
SELECT
    account
    , module
    , DdaAccount
FROM WithLowestDda
WHERE Row = 1