ROWID and rownum

Question

Hello World!
I have a large table I want to trancate to 10 rows.
I use the staement:
delete from aa where rowid in (select rowid from (select rowid from aa) where rownum > 11);
This result in 0 records deleted due to select rowid from (select rowid from aa) where rownum > 11; results in 0 records selected.
At the same time select rowid from (select rowid from aa) where rownum < 17;
produce correct result.
Any suugestions?
TIA

Answer 1

You should NOT use ";" symbol at the end of sql statement you call using
EXECUTE IMMEDIATE.
Change your function (and use binding variable whereever it's possible):
SQL> CREATE or replace function delete_rows (
  2  table_name IN VARCHAR2,
  3  nrows IN NUMBER DEFAULT NULL) return NUMBER IS
  4  l_sql VARCHAR2(32767);
  5  BEGIN
  6 
  7  IF TABLE_NAME IS NOT NULL and nrows IS NOT NULL THEN
  8   l_sql := 'delete from '||table_name ||
  9   ' where rowid not in (select rowid from (select rowid from '|
10   table_name||') where rownum < :1)';
11   EXECUTE IMMEDIATE l_sql using nrows;
12  END IF;
13 
14  commit;
15 
16  return null;
17 
18  EXCEPTION
19  WHEN OTHERS THEN
20   DBMS_OUTPUT.PUT_LINE(SQLERRM);
21   return null;
22  END delete_rows;
23  /
Function created.
SQL> select delete_rows('emp',11) from dual;
DELETE_ROWS('EMP',11)
ORA-14551: cannot perform a DML operation inside a query
SQL> begin
  2   dbms_output.put_line(delete_rows('emp',11));
  3  end;
  4  /
PL/SQL procedure successfully completed.Rgds.