Filtering a group

Question

Hi there,
I was wondering if you a had any suggestions on how to query a list of organisation.
The organisations are repeating (in a maximum of three each) because there is another class variable on the table that has different relevant values and NULL. So there exist an organisation with a class variable that contains NULL along with other relevant
values i.e.
WaterCorp --> 09/11/2014
WaterCorp --> 10/12/2010
WaterCorp --> NULL
CorpWater --> 05/11/1957
CorpWater --> 06/05/2013
DrinkWater --> NULL
My question, how can a report be produced using SQL that will only return organisation name 'DrinkWater' because it has a class variable of NULL and not 'WaterCorp'?
Thanks,

Answer 1

Another method could be
CREATE TABLE #t (id VARCHAR(20), dt DATE)
INSERT INTO #t VALUES ('WaterCorp','20141109')
INSERT INTO #t VALUES ('WaterCorp','20141108')
INSERT INTO #t VALUES ('WaterCorp',NULL)
INSERT INTO #t VALUES ('CorpWater','20141110')
INSERT INTO #t VALUES ('CorpWater','20141111')
INSERT INTO #t VALUES ('DrinkWater',NULL)
INSERT INTO #t VALUES ('TypeWater','20141112')
SELECT * FROM 
(SELECT * ,COUNT(*) OVER (PARTITION BY id) cn
 FROM #t 
 ) AS Der WHERE cn=1 AND dt IS NULL
Best Regards,Uri Dimant SQL Server MVP,
http://sqlblog.com/blogs/uri_dimant/
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