declare @target table (Cocode char(2), Brcode char(2), Loccode char(2), [Month] int, [Year] int, target int);
declare @TargetFormat table (Cocode char(2), Brcode char(2), Loccode char(2), Apr_T int, May_T int, Jun_T int);

insert into @target values
('C1', 'B1', 'L1', 4, 2014, 100),
('C1', 'B1', 'L1', 5, 2014, 120),
('C1', 'B1', 'L1', 6, 2014, 140);

insert into @TargetFormat values
('C1', 'B1', 'L1', 0, 0 ,0);

with 
targetupvt as (
	select Cocode, Brcode, Loccode,
	    case month
			when 'Apr_T' then 4
			when 'May_T' then 5
			when 'Jun_T' then 6
			end as month, 
		target

	from @TargetFormat
	unpivot (target for month in (Apr_T, May_T, Jun_T)) u
),
targetbymonth as (
    select ca.*
	from @target T
	cross apply (
		select tf.month, t.target
		from targetupvt tf
		where  TF.Cocode=T.Cocode and TF.Brcode=T.Brcode and TF.Loccode=T.Loccode and tf.month = t.Month and T.Year=2014
	) ca
)

update @TargetFormat
set Apr_T = p.[4],
    May_T = p.[5],
	Jun_T = p.[6]

from targetbymonth
pivot(max(target) for month in ([4],[5],[6])) p

select * from @targetFormat