Appending to a zero length clob

Question

9.2.0.6
this works:
var myClob clob
begin
:myClob := to_clob(' ');
for rec in (select * from delme1) loop
dbms_lob.append(:myClob
,to_clob(rec.ename || '\n'));
end loop;
end;
but this does not
var myClob clob
begin
:myClob := to_clob('');
for rec in (select * from delme1) loop
dbms_lob.append(:myClob
,to_clob(rec.ename || '\n'));
end loop;
end;
Seems like it does not like appending to a zero length clob. other than some trim thing how can I start at line zero.
Thanks

Answer 1

If you want to grasp an understanding about zero length strings then you should make yourself a coffee (or you may need several cups) and take a read of this thread:
Treatment of zero-length strings as NULLs?
But in short you should note that using a string '' is not a zero length string, but is considered to be NULL. Therefore your original clob, when using this is NULL.
Consider the following instead...
SQL> declare
  2    myClob clob;
  3  begin
  4  --  :myClob := to_clob('');
  5    for rec in (select ename from emp)
  6    loop
  7      IF NVL(dbms_lob.getlength(myClob),-1) < 1 THEN
  8        myClob := to_clob(rec.ename || '\n');
  9      ELSE
10        dbms_lob.append(myClob, to_clob(rec.ename || '\n'));
11      END IF;
12    end loop;
13    dbms_output.enable(1000000);
14    dbms_output.put_line('Length');
15    dbms_output.put_line(NVL(dbms_lob.getlength(myClob),-1));
16  end;
17  /
Length
98
PL/SQL procedure successfully completed.
SQL>