Trigger SEQ column for every new value of ID it should start from 1

Question

I have
table table_A
(ID NUMBER,
SEQ NUMBER,
DETAIL VARCHAR2(2000))
In this table ID and SEQ are combined primary key
Data looks like
ID     SEQ     DETAIL
1000     1     COMMENTS1
1000     2     COMMENTS2
1001     1     COMMENTS3
1002     1     COMMENTS4
1002     2     COMMENTS5
1002     3     COMMENTS6
1003     1     COMMENTS7
I have ID as oracle generated seq Number , but I need trigger to generate SEQ column value for every new value of ID it should start from 1

Answer 1

This is probably not something you would want to do in a trigger. You would generally be much better off storing ID and detail in the table and generating SEQ in a view, i.e.
CREATE VIEW my_view
AS
SELECT id,
       DENSE_RANK() OVER( PARTITION BY id ORDER BY <<something>>) seq,
       detail
  FROM table_AUnless you can guarantee that only one session will be inserting data at a time, I don't see how you could make a trigger work here.
Justin
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC