Question

i have the table as below,
i would like to find the max(account_opened_date), if there is null date is existing, i have to show null values.

Scenario1

Table1

CLIENTID            ACCOUNTID           ACCOUNT_OPENED_DATE
11562               3880                07/05/2012
11562               3884                08/05/2012
11562               3885                09/06/2012
11562               3886                10/06/2012
11562               3881                NULL
11562               3882                NULL  

the results are as below.

CLIENTID            ACCOUNTID           ACCOUNT_OPENED_DATE  
11562               3882                NULL  

in the above scenario, i have to take null because, there is null values existing in account opened dates

Scenario2

Table1

CLIENTID            ACCOUNTID           ACCOUNT_OPENED_DATE  
11563               3880                07/05/2012
11563               3884                08/05/2012
11563               3885                09/06/2012
11563               3886                10/06/2012
11563               3881                11/10/2011
11563               3882                10/22/2012  

The results ARE AS below.

CLIENTID            ACCOUNTID           ACCOUNT_OPENED_DATE
11563               3882                10/22/2012  

in the above scenario, i have to take 10/22/2012 because, there is no null values existing in account opened dates
PLEASE HELP!

Answer 1

Try this

SELECT * FROM (
SELECT CLIENTID, ACCOUNTID, ACCOUNT_OPENED_DATE, 
ROW_NUMBER() OVER (partition by clientid 
             ORDER BY CASE WHEN ACCOUNT_OPENED_DATE IS NULL THEN '12/31/9999' 
                      ELSE ACCOUNT_OPENED_DATE END DESC) opened_date_rank
FROM dbo.Table1
) v WHERE opened_date_rank = 1 

Example:

declare @table table (clientid int, accountid int, opened_date date)
insert into @table 
select 11562, 3880, '07/05/2012' UNION ALL
select 11562,3884, '08/05/2012' UNION ALL
select 11562,3882, null UNION ALL
select 11563,3880, '07/05/2012' UNION ALL
select 11563,3884, '08/05/2012' UNION ALL
select 11563,3882,'10/22/2012'



SELECT * FROM (
SELECT clientid, accountid, opened_date, 
row_number() over (partition by clientid 
             ORDER BY CASE WHEN opened_date IS NULL THEN '12/31/9999' 
                      ELSE opened_date END DESC) opened_date_rank
FROM @table
) v where opened_date_rank = 1