Oracle:copie linha ao atualizar um campo para tabela com muitas colunas

-- setup test table
create table my_table(pk, value) as
  select 17 pk, 'abc' value from dual;

declare
  l_data my_table%rowtype;
begin
  -- fetch the row we want to copy
  select * into l_data from my_table tbl where tbl.pk = 17; 
  -- update all fields that need to change
  l_data.pk := 18;
  -- note the lack of parens around l_data in the next line
  insert into my_table values l_data; 
end;