Modifying this trigger

Question

dear all;
I need to modify this simple trigger to occur for these cases
create or replace trigger expiry_sync
after update on table_two
for each row
begin
   update table_one i
      set i.expiry =
         case
           when :new.period = 'Years'
            then
               add_months(i.begin_date, :new.life_number * 12)
            when :new.period  = 'Months'
            then
               add_months(i.begin_date, :new.life_number)
            when :new.period = 'Days'
            then
               i.begin_date + :new.life_number
         end
   where
     i.part_number = :new.part_number
     and i.i_vendors = :new.vendors;
end;now i would like to include this case as well...basically if we have a situation where the i_vendor doesnt match with the :new.vendors from table_two, then it should check to see if there is a vendor that says default in the table_two and if there is one then it should go with the fields/characteristics associated with the default vendor....
Edited by: user13328581 on Feb 3, 2011 8:19 AM

Answer 1

Hi,
The reason I confused you with my two-trigger suggestion was that I mis-understood what you want to do. Could you please post an example or tow of a normal update (where you don't have to use a default vendor) and an abnormal update (where you do)?
That is, assume the tables are as you posted them earlier. Post a couple of UPDATE statements for table_two, and show me what table_one should look like after each one.
Here's an example of a package that asigns values to SYS_CONTEXT variables. The package has 2 procedures, for modualrity:
(1) set_all finds all the 'DEFAULT' rows in table_two, and, for each such row, assigns values to a couple of variables
(2) set_var assigns a given value to a given variable
This assumes that your schema name is FUBAR. It creates a SYS_CONTEXT namespace called TABLE_TWO_DEFAULT, and a package called TABLE_TWO_PKG that can assign variables in that namespace. (Any procedure or query can call SYS_CONTEXT to read the variables in the namespace; no special pivileges are required.)
CREATE OR REPLACE PACKAGE  table_two_pkg
AS
PROCEDURE     set_all
PROCEDURE     set_var
(     in_name          IN     VARCHAR2
,     in_text          IN     VARCHAR2     DEFAULT     NULL     -- New value
END     table_two_pkg;
SHOW ERRORS
CREATE OR REPLACE PACKAGE BODY  table_two_pkg
AS
--     NOTE: Before using this package, SYSTEM (or some other authorized user)
--     must issue the following SQL statement:
--          CREATE OR REPLACE CONTEXT table_two_default USING fubar.table_two_pkg;
--     The preceding only needs to be doen once in the lifetime of the application.
--          **   s e t _ a l l   **
--          set_all
PROCEDURE     set_all
IS
BEGIN
     FOR  d_rec  IN  ( SELECT  *
                          FROM       table_two
                 WHERE       vendors     = 'DEFAULT'
     LOOP
          dbms_output.put_line (d_rec.period || '= period in set_all');
          set_var ( d_rec.id || '_LIFE_NUMBER'
               , TO_CHAR (d_rec.life_number)
          set_var ( d_rec.id || '_PERIOD'
               , d_rec.period)
     END LOOP;
END     set_all
--          **   s e t _ v a r   **
--          set_var assigns a vlaue to a single variable in the
--          table_two_default namespace.
PROCEDURE     set_var
(     in_name          IN     VARCHAR2
,     in_text          IN     VARCHAR2     DEFAULT     NULL     -- New value
IS
BEGIN
     dbms_session.set_context
          'TABLE_TWO_DEFAULT',
          in_name,
          in_text
END     set_var;
END     table_two_pkg;
SHOW ERRORS
EXEC table_two_pkg.set_all;After you have run set_all, then, instead of querying table_two like this:
SELECT     period
INTO     v_period
FROM     table_two
WHERE     id     = 'C'
AND     vendors     = 'DEFAULT';you can simply do this:
v_period := SYS_CONTEXT ( 'TABLE_TWO_DEFAULT'
                   , 'C_PERIOD'
               );Since table_two is only queried when set_all is called, you can use SYS_CONTEXT in a trigger on table_two.
This job is a little more confusing than some SYS_CONTEXT applications, because (as I understand it) you want something two-dimensional , that is, might want any column from any row of table_two. I combined those two dimesions into one, by changing what would otherwise be varibale names like LIFE_NUMBER or PERIOD to C_LIFE_NUMBER and C_PERIOD, where C is the id from that row. (This assumes that id is unique among DEFAULT rows.)