SQL query unique values based on 2 colums - sql-server-2008

Question

I need help figuring this out.
At the moment I have this query:
SELECT Table1.Column1 AS Company
,SUM(DATEDIFF(Day, Table2.Column2, Table1.Column3)) AS DiffDate
FROM Table1
INNER JOIN Table2 ON Table1.Column6 = Table2.Column6
AND Table1.Column5 = Table2.Column5
GROUP BY Company
The result of this is...
Company DiffDate
company1 8
But this is not what I want because there are values that are the combinations of column5 and column6 that are the same. See below.
Company | Column6 | Column5 | DiffDate
Company1 | 5782 | 10 | 2
Company1 | 5782 | 10 | 2
Company1 | 5782 | 20 | 2
Company1 | 5782 | 30 | 2
So the result I'm after is 6, not 8.
I tried using SELECT DISTINCT but that doesn't do anything.
Thank you in advance.
edit 2016-02-09
I've made the following query in SSMS.
;WITH cte AS (SELECT DISTINCT bestlevdat, bestradnr, bestnr FROM dbo.bpa)
SELECT dbo.bp.ftgnr AS Företagsnr,SUM(DATEDIFF(Day,cte.bestlevdat, dbo.bp.bestberlevdat)) AS Diff_Bekräftat_dat,
SUM(DATEDIFF(Day,cte.bestlevdat, dbo.bp.bestbeglevdat)) AS Diff_Önskat_dat, COUNT(dbo.bp.bestradnr) AS AntalRader, SUM(CASE WHEN datediff(day, cte.bestlevdat, dbo.bp.bestberlevdat) < - 0 THEN 1 ELSE 0 END) AS Antal_avvikande_rader, ROUND((COUNT(dbo.bp.bestradnr) - SUM(CASE WHEN datediff(day, cte.bestlevdat, dbo.bp.bestberlevdat) < - 0 THEN 1.0 ELSE 0.0 END)) * 100 / COUNT(dbo.bp.bestradnr), 1) AS Levsäk
FROM dbo.bp INNER JOIN
cte ON dbo.bp.bestnr = cte.bestnr AND dbo.bp.bestradnr = cte.bestradnr
WHERE (YEAR(dbo.bp.bestberlevdat) = '2015')
GROUP BY dbo.bp.ftgnr
ORDER BY AntalRader DESC
This works a charm. But when I create a new view and paste this query there and try to save I get an error on the ";" again. If I remove ";" in SSMS I get error "The multi-part identifier "cte.bestlevdat" could not be bound" and also converts my query to the following:
WITH cte AS (SELECT DISTINCT bestlevdat, bestradnr, bestnr
FROM dbo.bpa AS bpa_1)
SELECT TOP (100) PERCENT dbo.bp.ftgnr AS Företagsnr, SUM(DATEDIFF(Day, cte_1.bestlevdat, dbo.bp.bestberlevdat)) AS Diff_Bekräftat_dat, SUM(DATEDIFF(Day,
cte_1.bestlevdat, dbo.bp.bestbeglevdat)) AS Diff_Önskat_dat, COUNT(dbo.bp.bestradnr) AS AntalRader, SUM(CASE WHEN datediff(day, cte.bestlevdat,
dbo.bp.bestberlevdat) < - 0 THEN 1 ELSE 0 END) AS Antal_avvikande_rader, ROUND((COUNT(dbo.bp.bestradnr) - SUM(CASE WHEN datediff(day, cte.bestlevdat,
dbo.bp.bestberlevdat) < - 0 THEN 1.0 ELSE 0.0 END)) * 100 / COUNT(dbo.bp.bestradnr), 1) AS Levsäk
FROM dbo.bp INNER JOIN
cte AS cte_1 ON dbo.bp.bestnr = cte_1.bestnr AND dbo.bp.bestradnr = cte_1.bestradnr
WHERE (YEAR(dbo.bp.bestberlevdat) = '2015')
GROUP BY dbo.bp.ftgnr
ORDER BY AntalRader DESC
Sorry if I've missed something obvious, but I'm pretty new with querys and this is my first attempt on "View".

Answer 1

Sounds like you want to do something like you want the distinct rows from Table2, and to join/aggregate them from Table1, so using a CTE may help, so something like:
;WITH cte AS (
SELECT DISTINCT
Column2,
Column5,
Column6
FROM Table2
)
SELECT
Table1.Column1 AS Company,
SUM(DATEDIFF(Day, cte.Column2, Table1.Column3)) AS DiffDate
FROM Table1
INNER JOIN cte
ON Table1.Column6 = cte.Column6
AND Table1.Column5 = cte.Column5
GROUP BY Company