select * from one where where_cond

union

select * from two where exists (select * from one where where_cond) [AND where_cond]

declare @Now char(8),

@AYearAgo char(8)

set @Now=convert(char(8),getdate(),112)

set @AYearAgo = convert(char(8),dateadd(year,-1,@Now),112)

select Field1, Field19 from MyTable where CreateDate between @AYearAgo and @Now

--or just use the one...

declare @t table ([Year] int, [ID] int, SubID int , Value int)

insert @t

select 1990, 1, 1, 12 union all

select 1991, 1, 1, 15 union all

select 1992,...