Return the Minimum from two tables in a Union

Question

Hello
I have written a simple union query from our dialler service which has 2 tables, in inbound and an outbound table. A lead can show in any table depending how they came through to an agent and they can also show in both tables.  I need to return the
the first instance in the calltime column from both tables but also return all the other information.  I'm expecting multiple entries for the minimum calltime which is fine, I will be using a lookup in excel to extract the time.  Just to make matters
a little more difficult i'm having to use the OPENQUERY function because its within MYSQL.
SELECT O.Lead, O.DataList, O.[CallTime] AS 'CallDate', O.[Status], O.Uniqueid, O.Campaign, O.number, O.Advisor, 'Outbound' AS CallType
FROM OPENQUERY (dialler, 'SELECT * FROM dialler_outbound_data') O
WHERE O.CallTime >= '2014-12-01'
UNION
SELECT I.Lead, I.DataList, [CallTime] AS 'CallDate', I.[Status], I.Uniqueid, I.Campaign, I.Number, I.Advisor, 'Inbound' AS CallType
FROM OPENQUERY (dialler, 'SELECT * FROM dialler_inbound_data') I
WHERE I.CallTime >= '2014-12-01'
Can anyone help please?
Many Thanks
Rich

Answer 1

Hi Rich,
The use of the ROW_NUMBER function as mentioned and temp tables should do the trick.  See the code below...hope this helps.
SELECT ROW_NUMBER() OVER(ORDER BY O.[CallTime]) as 'Occurrance'
,O.Lead
,O.DataList
,O.[CallTime] AS 'CallDate'
,O.[Status]
,O.Uniqueid
,O.Campaign
,O.number
,O.Advisor
,'Outbound' AS CallType
INTO #TEMP1
FROM OPENQUERY (dialler, 'SELECT * FROM dialler_outbound_data') O
WHERE O.CallTime >= '2014-12-01'
SELECT ROW_NUMBER() OVER(ORDER BY I.[CallTime]) as 'Occurrance'
,I.Lead
,I.DataList
,[CallTime] AS 'CallDate'
,I.[Status]
,I.Uniqueid
,I.Campaign
,I.Number
,I.Advisor
,'Inbound' AS CallType
INTO #TEMP2
FROM OPENQUERY (dialler, 'SELECT * FROM dialler_inbound_data') I
WHERE I.CallTime >= '2014-12-01'
INSERT INTO #FINAL
SELECT * FROM #TEMP1
UNION
SELECT * FROM #TEMP2
SELECT * FROM #FINAL AS F WHERE F.Occurrance = 1
I'm new to this so if this helps, I could use your vote. 
Thanks,
 Zach