declare @表1 table 
(ID int,A类型 varchar(2),B类型 varchar(2),C类型 varchar(2))
insert into @表1
select 1,'a1','b1','c1' union all
select 2,'a2','b2','c2' union all
select 3,'a3','b3','c3'

;with maco as
(
    select ID,A类型 from @表1
    union 
    select ID,B类型 from @表1
    union 
    select ID,C类型 from @表1
)

select id,char(64+row_number() over (partition by id order by a类型)) as 类型,A类型 from maco

/*
ID          类型   A类型
----------- ---- ----
1           A    a1
1           B    b1
1           C    c1
2           A    a2
2           B    b2
2           C    c2
3           A    a3
3           B    b3
3           C    c3

*/