Driving processing with user defined rules

Question

Hi,
I am looking for some examples of user defined rules for file processing.
So I have a file loaded in to the application in a staging table, user will want to define rules to process the data and then an output will be created.
Very vague question I know but has anyone got any examples where they did something similar which might help?
Thanks.

Answer 1

Roger,
Here's one that I found that may not look very simple but it actually is if you just break it down piece by piece.
create or replace FUNCTION              "SQL_IP_SUBNET" (
p_octet1 in varchar2,
p_octet2 in varchar2,
p_octet3 in varchar2,
p_octet4 in varchar2,
p_slash in varchar2,
p_status in varchar2)
return varchar2
as
l_select varchar2(1000);
l_octet1 varchar2(200);
l_octet2 varchar2(200);
l_octet3 varchar2(200);
l_octet4 varchar2(200);
l_slash varchar2(200);
l_status varchar2(200);
l_cidr varchar2(50);
l_where varchar2(1000);
l_order_by varchar2(100);
l_sql varchar2(32767);
begin
l_select := q'!select id, get_ip_addr(octet1, octet2, octet3, octet4) ip_addr, slash, description, !';
l_select := l_select || q'! octet1, octet2, octet3, octet4 from poc_subnets where 1=1!';
if (p_octet1 is not null) then
l_octet1 := q'! and octet1=!' || p_octet1;
end if;
if (p_octet2 is not null) then
l_octet2 := q'! and octet2=!' || p_octet2;
end if;
if (p_octet3 is not null) then
l_octet3 := q'! and octet3=!' || p_octet3;
end if;
if (p_octet4 is not null) then
l_octet4 := q'! and octet4=!' || p_octet4;
end if;
if (p_slash is not null) then
if substr(p_slash,1,1) != '/' and length(p_slash) = 2 then
  l_cidr := '/'||p_slash;
else
  l_cidr := p_slash;
end if;
l_slash := q'! and slash='!' || l_cidr || q'!'!';
end if;
if length(l_octet1) > 0 then
l_where := l_octet1;
end if;
if length(l_octet2) > 0 then
l_where := l_where || l_octet2;
end if;
if length(l_octet3) > 0 then
l_where := l_where || l_octet3;
end if;
if length(l_octet4) > 0 then
l_where := l_where || l_octet4;
end if;
if length(l_slash) > 0 then
l_where := l_where || l_slash;
end if;
if length(p_status) > 0 then
case
  when p_status = 'YES' then
   l_status := q'! and assigned = 'YES'!';
  when p_status = 'NO' then
   l_status := q'! and assigned = 'NO'!';
  else
   l_status := null;
end case;
end if;
if length(l_status) > 0 then
l_where := l_where || l_status;
end if;
-- do the order by clause
l_order_by := q'! order by octet1, octet2, octet3, octet4!';
if length(l_where) > 0 then
l_sql := l_select||l_where||l_order_by;
else
l_sql := l_select||l_order_by;
end if;
return l_sql;
end;
Just so you know, this is not necessarily the best way to do what you're asking. It does get the job done however.
If you inspect the code it's basically just a bunch of string concatenation operations based on the presence or absence of each of the input parameters. Pretty much what you were asking about.
Earl