Question

Suppose I have an sql statement

select a.Date, count(a.Id) as Apples from dbo.apples as a group by a.Date

which yields a result

Date      Apples
10/1/2011 4
10/2/2011 6
10/4/2011 8

And I have a second query

select o.Date, count(o.Id) as Oranges from dbo.Oranges as o group by o.Date

which yields the result

Date      Oranges
10/2/2011 3
10/3/2011 5
10/4/2011 7

I would like to combine the two results into a single result like

Date      Apples Oranges
10/1/2011 4      0
10/2/2011 6      3
10/3/2011 0      5
10/4/2011 8      7

I tried

select select a.Date, count(a.Id) as Apples from dbo.apples as a group by a.Date
union 
select o.Date, count(o.Id) as Oranges from dbo.Oranges as o group by o.Date

which didn’t give me the expected results, what I got was more like

Date      Apples
10/1/2011 4   
10/2/2011 6
10/2/2011 3
10/3/2011 5
10/4/2011 8
10/4/2011 7

with no mention of Oranges.

What should the final sql statement look like (I prefer performant and concise over not).

Answer 1

select date,sum(apples) as apples,sum(oranges) as Oranges
from
(
select a.Date as theDate, count(a.Id) as Apples,0 as Oranges 
from dbo.apples as a group by a.Date 
union all
select o.Date, 0 as apples, count(o.Id) as Oranges
 from dbo.Oranges as o 
 group by o.Date 
) xx
group by theDate