Question

I have a table with column names:

category1, category2, category3, Value

I want to get the following combinations from table:

---> category1,count(*)

---> category1, category2, count(*)

---> category2, category3, count(*)

Is there a way to do this in just one query or do I really need to write 3 separate queries? I am thinking of design like following:

Category1, Category2, Category3, CountNumber

Where the for case 1, category2 and category3 columns would be blank and for case 2 category 3 column would be blank, etc.

--------EXAMPLE---------------------------------------------------------
Cat1           Cat2          Cat3        Value
a              NULL           d1           13
b              e1             d1           13
a              e2             d1           13
c              NULL           d2           13
a              e1             d1           13
a              NULL           d1           13
--------DESIRED OUTPUT -------------------------------------------------
Cat1           Cat2           Cat3           CountNumber
a              NULL           NULL           4
b              NULL           NULL           1
c              NULL           NULL           1
a              e1             NULL           1
c              e1             NULL           0
NULL           e1             d1             2

and so on
Thanks

Answer 1

Try this

Select category1, null Category2, null category3, count(*)
from table
group by category1
UNION ALL
Select category1, category2, null category3, count(*)
from table
group by category1, category2
UNION ALL
Select null  category1,category2, category3, count(*)
from table
group by category2, category3

To insert rows in tmp table

SELECT * INTO TmpTable FROM (
Select category1, null Category2, null category3, count(*)
from table
group by category1
UNION ALL
Select category1, category2, null category3, count(*)
from table
group by category1, category2
UNION ALL
Select null  category1,category2, category3, count(*)
from table
group by category2, category3) x