Transpose column value into row SQL, Sql Server

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create table t (ID_NUMBER varchar(16), BK_no varchar(16), Res varchar(16));
insert into t values
 ('LUC00003','BK001','CLARETH')
,('LUC00003','BK001','MARC')
,('LUC00009','BK001','CLARETH')
,('LUC00009','BK001','MICHAEL')

select 
    id_number
  , bk_no
  , Res1 = max(case when rn = 1 then Res end)
  , Res2 = max(case when rn = 2 then Res end)
from (
  select *
    , rn = row_number() over (partition by id_number, bk_no order by res)
  from t
) sub
group by id_number, bk_no

/* dynamic version */

declare @cols nvarchar(max);
    declare @sql  nvarchar(max);
    
      select @cols = stuff((
        select distinct 
          ',' + quotename('Res'
              +convert(nvarchar(10),row_number() over (
                  partition by id_number, bk_no 
                  order by     res 
              ))
              )
          from t 
          for xml path (''), type).value('.','nvarchar(max)')
        ,1,1,'');
        
    select @sql = '
     select id_number, bk_no, ' + @cols + '
      from  (
        select 
            id_number
          , bk_no
          , Res
          , rn=''Res'' + convert(nvarchar(10),row_number() over (
                  partition by id_number, bk_no 
                  order by     res 
              ))
          from t
          ) as a
     pivot (max([Res]) for [rn] in (' + @cols + ') ) p';
     select @sql as CodeGenerated;
     exec sp_executesql @sql;

View schema
Execution time: 0,02 sec, rows selected: 7, rows affected: 4, absolute service time: 0,17 sec