Transpose Rows in Columns

Hey.

I need to transpose a Table.

That's how it looks like:

TABLE:

OBJEK     ATINN     ATWRT

1                   a               5

1                    b               8

1                    c               6

2                    b               4

2                    c                9

I want to have following structure:

TABLE2:

OBJEK     ATWRTa     ATWRTb     ATWRTc

1                    5               8               6

2                    ?               4               9

I thougt of following query:

select "OBJEK",

  (case when "ATINN" = 'a' then "ATWRT"  end) as "ATWRTa",

(case when "ATINN" = 'b' then "ATWRT" end) as "ATWRTb",

  (case when "ATINN" = 'c' then "ATWRT"  end) as "ATWRTc"

from

  "P1591085134"."AUSP1"

group by "OBJEK"

But the compiler tells me that "ATINN" is not a group by expression...

Without the group by command i get the following result:

OBJEK     ATWRTa     ATWRTb     ATWRTc

1                    5               ?               ?

1                    ?               8               ?

1                    ?               ?               6

2                    ?               4               ?

2                    ?               ?               9

Is there another possibility? Probably with a stored procedure?