-> prepare for DBD::Oracle::db (DBI::db=HASH(0x9b82ad8)~0x9b82b20 'in
+sert into swma_temp_table
(m_serial,m_start,m_end,m_stat,m_product)
select '10-641CH',to_date('2008-11-21', 'YYYY-MM-DD'),to_date('2011-07
+-31', 'YYYY-MM-DD'),'Active','694275O'
from dual 
where exists (select NULL from servers where host_serial='10-641CH')
') thr#999c008
    dbd_st_prepare'd sql INSERT (pl1, auto_lob1, check_sql1)
    dbd_describe skipped for INSERT
    <- prepare= DBI::st=HASH(0x9c5a8dc) at ./get_swma.pl line 57
    -> execute for DBD::Oracle::st (DBI::st=HASH(0x9c5a8dc)~0x9c558a8)
+ thr#999c008
   dbd_st_execute INSERT (out0, lob0)...
Statement Execute Mode is 32 (COMMIT_ON_SUCCESS)
    dbd_st_execute INSERT returned (SUCCESS, rpc1, fn3, out0)
    <- execute= 1 at ./get_swma.pl line 59
    -> STORE for DBD::Oracle::st (DBI::st=HASH(0x9c558a8)~INNER 'Trace
+Level' 4) thr#999c008
    STORE DBI::st=HASH(0x9c558a8) 'TraceLevel' => 4
    <- STORE= 1 at ./get_swma.pl line 60
    -> DESTROY for DBD::Oracle::st (DBI::st=HASH(0x9c558a8)~INNER) thr
+#999c008
    <- DESTROY= undef at ./get_swma.pl line 38 via  at ./get_swma.pl l
+ine 38
[download]

OK, tough nut to crack :)   Any chance to enable tracing on the Oracle side?

This trace suggests the execute worked as it returned 1. Whether a row was inserted or not is not discernible from this trace since you'd need to know what rows returned.