有人可以让我知道如何将下面的Oracle代码从Oracle转换为Postgres数据库:dbms_lob.writeappend()append()trim()write()
set serveroutput on;
declare
l_1 clob;
l_2 clob;
amount number;
offset number;
begin
select in_lob into l_1
from test.lob_table
where id=2 for update;
amount:=2;
offset:=3;
dbms_lob.writeappend(l_1,length('hhhhhhhh'),'hhhhhhhh');
dbms_output.put_line(l_1);
end;