3 tabeller i en tabel

SELECT a.Dato, a.aa, b.bb, c.cc
FROM (a INNER JOIN b ON a.Dato = b.Dato) INNER JOIN c ON a.Dato = c.Dato;

If you want to total for that each date then you can use
SELECT a.Dato, a.Antal, b.Antal, c.Antal, [a].[Antal]+[b].[antal]+[c].[antal] AS Tot
FROM (a INNER JOIN b ON a.Dato = b.Dato) INNER JOIN c ON b.Dato = c.Dato;

I (we) are also assuming that the date is a primary key (unique) Otherewise you need to group on Dato

SELECT a.Dato, Sum(a.Antal) AS SumOfAntal, Sum(b.Antal) AS SumOfAntal1, Sum(c.Antal) AS SumOfAntal2, Sum([a].[Antal]+[b].[antal]+[c].[antal]) AS Tot
FROM (a INNER JOIN b ON a.Dato = b.Dato) INNER JOIN c ON b.Dato = c.Dato
GROUP BY a.Dato;

cant help if you dont respond!

Sorry I was busy.

Det skal se sådan ud
"a.Dato a.produkt" "b.Dato b.Produkt" og "c.Dato c.produkt"
  1-1-03  a        2-1-03  b            3-1-03

Det skulle give
dato  a  b  c
1-1-03 a
2-1-03    b
3-1-03        c

lukker