Unexpected results from IF statement

Question

Can you please tell me why I am not dropping inside this IF statement as I would expect?
Snippet from PL/SQL script...
dbms_output.put_line('------------- TEMP DEBUG : About to enter for loop for existing licencees');
-- DELETE EXISTING LICENSEES THAT SHOULDN'T BE THERE
for r_existing_licensees in c_existing_licensees(r_licences.licenceid) loop
dbms_output.put_line('------------- TEMP DEBUG : Inside for loop for existing licencees where r_existing_licensees.customerid = [' || r_existing_licensees.customerid || ']');
dbms_output.put_line('------------- TEMP DEBUG : ................................r_licences.newcust1 = [' || r_licences.newcust1 || ']');
dbms_output.put_line('------------- TEMP DEBUG : ................................r_licences.newcust2 = [' || r_licences.newcust2 || ']');
dbms_output.put_line('------------- TEMP DEBUG : ................................r_licences.newcust3 = [' || r_licences.newcust3 || ']');
dbms_output.put_line('------------- TEMP DEBUG : ................................r_licences.newcust4 = [' || r_licences.newcust4 || ']');
dbms_output.put_line('------------- TEMP DEBUG : ................................r_licences.newcust5 = [' || r_licences.newcust5 || ']');
if r_existing_licensees.customerid <> r_licences.newcust1
and r_existing_licensees.customerid <> r_licences.newcust2
and r_existing_licensees.customerid <> r_licences.newcust3
and r_existing_licensees.customerid <> r_licences.newcust4
and r_existing_licensees.customerid <> r_licences.newcust5
then
dbms_output.put_line('------------- TEMP DEBUG :');
dbms_output.put_line('------------- TEMP DEBUG : .................................About to logically delete where r_existing_licensees.customerid = [' || r_existing_licensees.customerid || ']');
Log from DBMS_OUTPUT...
------------- TEMP DEBUG : About to enter for loop for existing licencees
------------- TEMP DEBUG : Inside for loop for existing licencees where
r_existing_licensees.customerid = [2805371]
------------- TEMP DEBUG : ................................r_licences.newcust1
= [2806250]
------------- TEMP DEBUG : ................................r_licences.newcust2
= []
------------- TEMP DEBUG : ................................r_licences.newcust3
= []
------------- TEMP DEBUG : ................................r_licences.newcust4
= []
------------- TEMP DEBUG : ................................r_licences.newcust5
= []
The bold, italic DBMS_OUTPUT lines never appear in the log, so I am NOT falling insided the IF statement even though the criteria are being met. What's the deal?
Thx in advance.
Guy

Answer 1

if r_existing_licensees.customerid <> r_licences.newcust1 and
   r_existing_licensees.customerid <> r_licences.newcust2 and
   r_existing_licensees.customerid <> r_licences.newcust3 and
   r_existing_licensees.customerid <> r_licences.newcust4 and
   r_existing_licensees.customerid <> r_licences.newcust5
thenit could be that some of your columns are nulls. try something like:
if nvl(r_existing_licensees.customerid,0) <> nvl(r_licences.newcust1,0) and
   nvl(r_existing_licensees.customerid,0) <> nvl(r_licences.newcust2,0) and
   nvl(r_existing_licensees.customerid,0) <> nvl(r_licences.newcust3,0) and
   nvl(r_existing_licensees.customerid,0) <> nvl(r_licences.newcust4,0) and
   nvl(r_existing_licensees.customerid,0) <> nvl(r_licences.newcust5,0)
then
note: assuming that they are number of datatypes.