Group by month with mutliple tables and date fields

Question

Good Day

I need to write a query which involves 3 tables. Each table has a date field. I want to run a query to group data by month eg

Month Costtotal Repairtotal Servicetotal

April 1243 2344 123123

May 3123 213123 21312

Each column comes from a different table that has its own date. Costtotal has purchasedate, repairtotal has repairdate and servicetotal has servicedate

Thanks in advance

Answer 1

select
    t.[Month]
    ,sum(t.Costtotal)
    ,sum(t.Repairtotal)
    ,sum(t.Servicetotal)
from 
(
    select
        Datepart(MM, PurchaseDate) as [Month],
        Costtotal,
        0 as Repairtotal,
        0 as Servicetotal
    from tablea

    union

    select
        Datepart(MM, RepairDate) as [Month],
        0 as Costtotal,
        Repairtotal,
        0 as Servicetotal
    from tableb

    union

    select
        Datepart(MM, ServiceDate) as [Month],
        0 as Costtotal,
        0 as Repairtotal,
        Servicetotal
    from tableb
) as t
group by t.[Month]
order by t.[Month]