Function and packages

Question

Hi friends ,
I have a requirement where in i need to decode values from my source table while inserting them into my target table. I usually do my task by making functions (don't use case and decode) . My first question is
1) Is using function to accomplish such tasks is good.I have numerous of such conversion requirement .
2)Clubbing subprograms togther into packages is a good habit .But what should be the number of such sub programs .Can i club togther 100 of such functions togther (an average function is of 50 lines) ? If not what should be the segregation thoughts?
3)Are the inbuilt oracle functions like sqrt,length etc deterministic ?
This code represents a typical requirement of mine where in I map my source country name into target's
country id while migrating my data from the source to the target .
create table source
emp_id number,
empname varchar2(100),
sal number,
country varchar2(100)
insert into source values (1,'ALEX',1000,'US');
Insert into source values (2,'RAHUL',2000,'IND');
Insert into source values (3,'KARTIK',3000,'IND');
Insert into source values (4,'SHADOW',5000,'US');
insert into source values(5,'LOUI',1500,'JAP');
Create table source_country_code
country varchar2(100),
abbrv  varchar2(100),
area number,
climate varchar2(100)
insert into source_country_code values ('UNITED STATES','US',10000,'COLD');
insert into source_country_code values ('INDIA','IND',100000,'HOT');
insert into source_country_code values ('JAPAN','JAP',1000000,'MODERATE');
Create table target_country_code
country_id number,
descr  varchar2(100),
density number,
weather varchar2(100)
insert into target_country_code values (101,'this is descrition txt 1',1001,'COLD');
insert into target_country_code values (102,'this is descrition txt 2',1001,'HOT');
insert into target_country_code values (103,'this is descrition txt 3',1001,'MODERATE');
create table target
emp_id number,
empname varchar2(100),
sal number,
country_id number
);i am typically making functions for such kind of mappings .I have numerous of such requirements as stated above and the
cardinality of the data is high .
create or replace function transform (in_src_country varchar2) return number deterministic
as
l_country_id number;
l_climate varchar2(1000);
begin
select climate into l_climate from source_country_code
   where upper(abbrv)=upper(in_src_country);
select country_id into l_country_id
from target_country_code
where upper(weather)=upper(l_climate);
return(l_country_id);
exception
when no_data_found then
return null;
end;final step ,
so ,what i usually do is
insert into target
select emp_id,empname,sal,transform(country) from source;
Thanks as always,
Rahul
Edited by: Rahul K on Jun 5, 2013 10:51 AM

Answer 1

Rahul  K wrote:
Hi friends ,
I have a requirement where in i need to decode values from my source table while inserting them into my target table. I usually do my task by making functions (don't use case and decode) . My first question is
1) Is using function to accomplish such tasks is good.I have numerous of such conversion requirement .Not really. If the functions are sufficiently complex then sometimes there's no way around it. However you're going to pay the price if you try to add this to a SQL query (your query won't scale in the least).
Rahul  K wrote:
2)Clubbing subprograms togther into packages is a good habit .But what should be the number of such sub programs .Can i club togther 100 of such functions togther (an average function is of 50 lines) ? If not what should be the segregation thoughts?Yeah, put as many as makes sense. Generally you would want to separate them in some logical fashion, by business function, or some other convention.
Rahul  K wrote:
3)Are the inbuilt oracle functions like sqrt,length etc deterministic ? http://docs.oracle.com/cd/E11882_01/appdev.112/e25518/adfns_packages.htm#ADFNS386
A deterministic function depends solely on the values passed into it as arguments and does not reference or modify the contents of package variables or the database or have other side-effects. Such a function produces the same result value for any combination of argument values passed into it.
So yes. They are.
Rahul  K wrote:
This code represents a typical requirement of mine where in I map my source country name into target's
country id while migrating my data from the source to the target .
create table source
emp_id number,
empname varchar2(100),
sal number,
country varchar2(100)
insert into source values (1,'ALEX',1000,'US');
Insert into source values (2,'RAHUL',2000,'IND');
Insert into source values (3,'KARTIK',3000,'IND');
Insert into source values (4,'SHADOW',5000,'US');
insert into source values(5,'LOUI',1500,'JAP');
Create table source_country_code
country varchar2(100),
abbrv  varchar2(100),
area number,
climate varchar2(100)
insert into source_country_code values ('UNITED STATES','US',10000,'COLD');
insert into source_country_code values ('INDIA','IND',100000,'HOT');
insert into source_country_code values ('JAPAN','JAP',1000000,'MODERATE');
Create table target_country_code
country_id number,
descr  varchar2(100),
density number,
weather varchar2(100)
insert into target_country_code values (101,'this is descrition txt 1',1001,'COLD');
insert into target_country_code values (102,'this is descrition txt 2',1001,'HOT');
insert into target_country_code values (103,'this is descrition txt 3',1001,'MODERATE');
create table target
emp_id number,
empname varchar2(100),
sal number,
country_id number
);i am typically making functions for such kind of mappings .I have numerous of such requirements as stated above and the
cardinality of the data is high .
create or replace function transform (in_src_country varchar2) return number deterministic
as
l_country_id number;
l_climate varchar2(1000);
begin
select climate into l_climate from source_country_code
where upper(abbrv)=upper(in_src_country);
select country_id into l_country_id
from target_country_code
where upper(weather)=upper(l_climate);
return(l_country_id);
exception
when no_data_found then
return null;
end;final step ,
so ,what i usually do is
insert into target
select emp_id,empname,sal,transform(country) from source;
Thanks as always,
Rahul
Edited by: Rahul K on Jun 5, 2013 10:51 AMYou would be much better (leaps and bounds better) off incorporating that logic directly into your SQL statement.
Cheers,