Query to return 1 instance of a record with duplicates

Question

INFO: I am working with Microsoft SQL.
Ok the title is confusing but here is an example of the table I\'m working with:

ID    Value    Signal    Read             


        

Answer 1

Similar query (uses CROSS APPLY and correlated subquery w/ TOP WITH TIES):

SELECT

        a.CustodianAccountNum,

        a.AccountName,

        a.AccountName2,

        a.AccountName3,

        a.AccountStartDate,

        a.AccountClosedDate,

        a.TaxableFederal,

        a.TaxableState,

        qq.ValuationDate,

        qq.MarketValue,

        cg.ClientGroupGUID as ClientGUID,

        c.ClientGUID as EntityGUID,

        convert (bit, case when b.cnt > 1 then 1 else 0 end) as IsDuplicate 



  FROM (

        SELECT      

              a.CustodianAccountNum,

              MIN(a.AccountID) as AccountID,

              count(*) as cnt

        FROM Accounts a



        WHERE

              a.AccountID in (SELECT AccountID from dbo.FnGetFilteredAccountIDs(@CurrentUserID)) -- apply permisssions

              and a.DeletedDate is null



        group by a.CustodianAccountNum

  ) b

  INNER JOIN Accounts a

  ON

        a.AccountID = b.AccountID



  INNER JOIN ClientAccounts ca

  ON

        a.AccountID = ca.AccountID

        and ca.DeletedDate is null

  INNER JOIN Clients c

  ON

        ca.ClientID = c.ClientID

        and c.DeletedDate is null



  INNER JOIN ClientGroups cg

  ON

        c.ClientGroupID = cg.ClientGroupID 

        and cg.DeletedDate is null

  CROSS APPLY 

  (

        SELECT 

              SUM(MarketValue) as MarketValue, 

              MIN(ValuationDate) as ValuationDate 

        FROM

              (SELECT TOP 1 WITH TIES arv.MarketValue, arv.ValuationDate 

              FROM AccountReturnValues arv 

              where 

                    arv.AccountId = a.AccountId 

                    and a.AccountClosedDate is null

              order by ValuationDate desc

              ) q

  ) qq