AutoPopulating a field with a string plus value from another field

Question

Hi: I have a table with two fields
create table LINKREQUEST (
requestid int primary key,
INCIDENT_NUMBER varchar2(16),
REQUESTID is auto populated using a sequence. I want to auto populate the INCIDENT field with the string "INC" plus the value from REQUESTID. Can someone help.
TIA
Ravi

Answer 1

REQUESTID is auto populated using a sequence. I want to auto populate the INCIDENT field with the string "INC" plus the value from REQUESTIDSomething like this?:
SQL> create table linkrequest (
requestid int primary key,
incident_number varchar2(16)
Table created.
SQL> create sequence linkrequest_seq
Sequence created.
SQL> create or replace trigger linkrequest_trg before insert on linkrequest
for each row
begin
select linkrequest_seq.nextval,
        case when :new.incident_number = 'INC' then 'INC' || linkrequest_seq.nextval else :new.incident_number end
   into :new.requestid, :new.incident_number from dual;
end;
Trigger created.
SQL> insert into  linkrequest (incident_number) values ('XY')
1 row created.
SQL> insert into  linkrequest (incident_number) values ('INC')
1 row created.
SQL> insert into  linkrequest (incident_number) values ('VW')
1 row created.
SQL> insert into  linkrequest (incident_number) values ('INC')
1 row created.
SQL> select * from linkrequest
REQUESTID INCIDENT_NUMBER
         1 XY             
         2 INC2           
         3 VW             
         4 INC4           
4 rows selected.