Regarding Functions

Question

Hi,
This is a piece of code that I'm stuck up with.
CREATE OR REPLACE FUNCTION NEW_DL_VALIDATION(link2 in varchar2,prottype in varchar2,vlink1type in varchar2,vlink1ckt in varchar2,vdla_ne in varchar2,
vdlz_ne in varchar2,vlink1aport1 in varchar2,vlink1zport1 in varchar2,vlink1aport2 in varchar2,
vlink1zport2 in varchar2)
return varchar2
is
newdl_stat varchar2(1);
vlink2 facodr%rowtype;
vnewdla_ne locref.clli%type;
vnewdlz_ne locref.clli%type;
begin
dbms_output.put_line('These are the inputs for 2nd function');
dbms_output.put_line('LINK2:' || link2);
dbms_output.put_line('prottype' || prottype);
dbms_output.put_line('LINK1:' || vlink1ckt);
begin
select ckt,type,layout,cac,a_port1,z_port1,a_port2,z_port2,prot1,a_location,z_location into vlink2.ckt,vlink2.type,vlink2.layout,vlink2.cac,
vlink2.a_port1,vlink2.z_port1,vlink2.a_port2,vlink2.z_port2,vlink2.prot1,vlink2.a_location,vlink2.z_location from facodr where ckt=link2
and stat='IE' and inter_domain='Y';
exception
when no_data_found then
dbms_output.put_line('The 2nd DL is not a valid one');
newdl_stat := 'N';
return newdl_stat;
end;
dbms_output.put_line('VLINK2.PROT1:' || vlink2.prot1);
select clli into vnewdla_ne from locref where cllikey=vlink2.a_location;
select clli into vnewdlz_ne from locref where cllikey=vlink2.z_location;
if vlink2.ckt!=vlink1ckt
then
if vlink2.type=vlink1type
then
if vlink2.prot1=prottype
then
if (vnewdla_ne=vdla_ne and vnewdlz_ne=vdlz_ne) or (vnewdla_ne=vdlz_ne and vnewdlz_ne=vdla_ne)
then
newdl_stat := 'Y';
return newdl_stat;
else
dbms_output.put_line('The locations or NEs of 2 DLs do not match');
newdl_stat := 'N';
return newdl_stat;
end if;
else
dbms_output.put_line('The protection types of the 2 DLs do not match');
newdl_stat := 'N';
return newdl_stat;
end if;
end;
Here in the third validation vlink2.prot1=prottype, the thing is that prottype is NULL. This variable is cominf from another function. Now when I checked vlink2.prot1 is also null. But when it tries to validate it tells me that both of them are not equal. its comapring NULL with NULL. How can I change this in order to make it work.
Thanks in advance

Answer 1

If you only want trap the situation in which both variables are NULL you might be better off with:
IF vlink2.prot1=prottype
OR (vlink2.prot1 IS NULL AND prottype IS NULL)
THEN
   ...Using NVL() runs the risk of false positives, although the risk may be negligible.
Cheers, APC