How to generate a query where dynamic column name?

Are you guaranteed to have the same number of A,B,C records? Also are there any other columns in that table? This table structure doesn't make much sense.

--> 测试数据: @T1
declare @T1 table (col1 varchar(1),col2 varchar(5))
insert into @T1
select 'A','Ali' union all
select 'B','Abu' union all
select 'C','Kawan' union all
select 'A','Bayu' union all
select 'B','Cawam' union all
select 'C','didik'

if object_id('tempdb..#') is not null
	drop table #
select *
into #
from @T1 a
order by col1


alter table # add flag int
go
declare @i int
set @i = 0
declare @c varchar(10)
set @c = ''
update a set
	@i = case when @c = col1 then @i+1 else 1  end
	,flag = @i
	,@c = col1
from # a


select 
	a= max(case when col1 = 'a' then col2 else '' end)
	,b = max(case when col1 = 'b' then col2 else '' end)
	,c =max( case when col1 = 'c' then col2 else '' end)
from #
group by flag

a     b     c     
----- ----- ----- 
Ali   Cawam Kawan
Bayu  Abu   didik

（所影响的行数为 2 行）

Can not understand your requirement + table design is not up to the mark. Also hard coding values may not help you.