Multiple Sums with different where clauses in same query result set

问题

I have a few tables that I am joining together and selecting various columns and sums from it and i want to combine the select statements so that all results are in the same results set. i currently have a query like:

declare @year INT
declare @month INT
set @year = '2013'
set @month = '08'

select CAST(LEFT(b.name, 3) AS varchar(3))AS Region, a.model, sum(a.Number)AS Uniques
from Table1 a
inner join database2.....table2 b
on a.code = b.code
where Year(a.EventDate) = @year
and Month(a.EventDate) = @month
and a.make='Toyota'
group by CAST(LEFT(b.name, 3) AS varchar(3)), a.model
order by CAST(LEFT(b.name, 3) AS varchar(3))

This brings up a dataset which looks something like:

Region   Model    Uniques
EST      Toyota      200
EST      Honda       350
CEN      Toyota      220
CEN       VW         150

I then have another similar query, but which uses different tables and requirements:

select CAST(LEFT(c.name, 3) AS varchar(3)) AS Region, a.Model, sum(b.Number)As Sales
from Table1 a
left join Table3 b
on a.leadid = b.leadid
inner join Database1..Table2 c
on a.code = c.code
where Year(a.EventDate) = @year
and Month(a.EventDate) = @month
and a.make='Toyota'
group by a.Model, CAST(LEFT(c.Name, 3) AS varchar(3))
order by CAST(LEFT(c.Name, 3) AS varchar(3))

this brings up a similar results set:

 Region      Model       Sales
    EST      Toyota      150
    CEN       VW         80
    CEN      Toyota      75

I just want to pair these results or make a joined query so I can have results like;

Region    Model       Uniques    Sales
EST       Toyota      200         150
EST       Honda       350          0
CEN       Toyota      220         75
CEN       vW          150         80

There are maybe 20-30 combinations of Region/Model that exist in total, and they are the same for each result set.

回答1:

Well, if you cannot do it all in one query, then you can simply join the 2 queries together:

select
t1.region,
t1.model,
t1.uniques,
t2.sales
from
(select CAST(LEFT(b.name, 3) AS varchar(3))AS Region, a.model, sum(a.Number)AS Uniques
from Table1 a
inner join database2.....table2 b
on a.code = b.code
where Year(a.EventDate) = @year
and Month(a.EventDate) = @month
and a.make='Toyota'
group by CAST(LEFT(b.name, 3) AS varchar(3)), a.model
order by CAST(LEFT(b.name, 3) AS varchar(3))
) t1 
inner join
(
select CAST(LEFT(c.name, 3) AS varchar(3)) AS Region, a.Model, sum(b.Number)As Sales
from Table1 a
left join Table3 b
on a.leadid = b.leadid
inner join Database1..Table2 c
on a.code = c.code
where Year(a.EventDate) = @year
and Month(a.EventDate) = @month
and a.make='Toyota'
group by a.Model, CAST(LEFT(c.Name, 3) AS varchar(3))
order by CAST(LEFT(c.Name, 3) AS varchar(3))
) t2
on t1.region = t2.region 
and t1.model = t2.model

回答2:

Use this concept:

SUM ( CASE WHEN ConditionIsMet THEN Column1 ELSE 0 END ),
SUM ( CASE WHEN OtherCondIsMet THEN Column2 ELSE 0 END )

来源：https://stackoverflow.com/questions/20530617/multiple-sums-with-different-where-clauses-in-same-query-result-set