How to avoid repeatation of code

Question

hi
My code is as mentioned below.
if l_location ='USA'
insert into location
select f1,f2,f3,f4
from usa_tab
else if l_location = 'FRANCE'
insert into location
select f1,f2,f3,f4
from france_tab f , x1_tab x
where f.id = x.id
else if l_location = 'UK'
insert into location
select f1,f2,f3,f4
from uk_tab u,y1_tab y
where u.id = y.id
end if;
how to avoid the repeatation of code here?

Answer 1

954992 wrote:
it is an existing application. The tables can not be changed.
actually here the insert and select statements are fixed , only the from and where conditions are getting changed.
howf to avoid repeatation of the fixed code?Oracle supports features called "+partition views+" and "+instead of triggers+". This can be used to glue tables (same structure) together and select and insert against these tables via a view.
Basic example:
// tables that constitutes the partition view - a check constraint on
// country is used to specify which cities are in which table, similar
// to a partition key
SQL> create table location_france(
  2          country varchar2(10) default 'FRANCE' not null,
  3          city    varchar2(20) not null,
  4          --
  5          constraint chk_france check (country in 'FRANCE'),
  6          constraint pk_location_france primary key
  7          ( country, city )
  8  ) organization index;
Table created.
SQL> create table location_uk(
  2          country varchar2(10) default 'UK' not null,
  3          city    varchar2(20) not null,
  4          --
  5          constraint chk_uk check (country in 'UK'),
  6          constraint pk_location_uk primary key
  7          ( country, city )
  8  ) organization index;
Table created.
SQL> create table location_spain(
  2          country varchar2(10) default 'SPAIN' not null,
  3          city    varchar2(20) not null,
  4          --
  5          constraint chk_spain check (country in 'SPAIN'),
  6          constraint pk_location_spain primary key
  7          ( country, city )
  8  ) organization index;
Table created.A partition view is a view that uses union all to glue these tables together:
SQL> create or replace view locations as
  2          select * from location_france
  3          union all
  4          select * from location_uk
  5          union all
  6          select * from location_spain
  7  /
View created.To support inserts against the partition view, an instead-of trigger is used:
SQL> create or replace trigger insert_location
  2          instead of insert on locations
  3  begin
  4          case :new.country
  5                  when 'FRANCE' then
  6                          insert into location_france values( :new.country, :new.city );
  7                  when 'UK' then
  8                          insert into location_uk values( :new.country, :new.city );
  9                  when 'SPAIN' then
10                          insert into location_spain values( :new.country, :new.city );
11          else
12                  raise_application_error(
13                          -20000,
14                          'Country name ['||:new.country||'] is not supported.'
15                  );
16          end case;
17  end;
18  /
Trigger created.Rows can now be inserted into the view and the trigger will ensure that the rows wind up in the correct table.
SQL> insert into locations values( 'FRANCE', 'PARIS' );
1 row created.
SQL> insert into locations values( 'UK', 'LONDON' );
1 row created.
SQL> insert into locations values( 'SPAIN', 'BARCELONA' );
1 row created.As with a partition table, a select on a partition view that uses the "partition column" (in this case, the COUNTRY column), the CBO can prune the non-relevant tables from the view and only select against the relevant table. In the following example, the UK is used as country filter and the CBO shows that only table LOCATION_UK is used.
SQL> set autotrace on explain
SQL> select * from locations where country = 'UK';
COUNTRY    CITY
UK         LONDON
Execution Plan
Plan hash value: 1608298493
| Id  | Operation           | Name               | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT    |                    |     1 |    19 |     1   (0)| 00:00:01 |
|   1 |  VIEW               | LOCATIONS          |     1 |    19 |     1   (0)| 00:00:01 |
|   2 |   UNION-ALL         |                    |       |       |            |          |
|*  3 |    FILTER           |                    |       |       |            |          |
|*  4 |     INDEX RANGE SCAN| PK_LOCATION_FRANCE |     1 |    19 |     2   (0)| 00:00:01 |
|*  5 |    INDEX RANGE SCAN | PK_LOCATION_UK     |     1 |    19 |     2   (0)| 00:00:01 |
|*  6 |    FILTER           |                    |       |       |            |          |
|*  7 |     INDEX RANGE SCAN| PK_LOCATION_SPAIN  |     1 |    19 |     2   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   3 - filter(NULL IS NOT NULL)
   4 - access("COUNTRY"='UK')
   5 - access("COUNTRY"='UK')
   6 - filter(NULL IS NOT NULL)
   7 - access("COUNTRY"='UK')
Note
   - dynamic sampling used for this statement (level=2)
SQL>Oracle provides a number of methods to address flawed data models and problematic client code. However, despite this flexibility on Oracle's part, you should still consider fixing the flawed design and code - as that flaws invariable mean reducing flexibility, performance and scalability.