About Sequences

Question

Hi Experts,
When I am entering the numbers by using sequence if the inserting data DML command fails, then the sequence no jumpts to next number even though that transaction is not successful.
I mean for a table I am entering the unique no's by using Myseq.nextval and name(here for name I have used primary key constraint so it won't accept duplicates) .
If the name is already there in the database, then that DML command won't be succeeded.
At the second attempt if it successes then automatically the next no is entered.
ie if 6 entered then no 7 is failed due to some constraint problem , then no 8 is inserted
I think you got the point what i am trying to say.
Please help me out

Answer 1

Hi Marc
Yes you are right, in case of a shutdown normal (but not shutdown abort) you will have back the "cached" values. Thanks for the remark.
SQL> create sequence seq_test start with 1 cache 1000;
Creata sequenza.
SQL> select seq_test.nextval from dual;
   NEXTVAL
         1
<br>
SQL> select seq_test.nextval from dual;
   NEXTVAL
         2
<br>
SQL> select seq_test.nextval from dual;
   NEXTVAL
         3
<br>
SQL> select seq_test.nextval from dual;
   NEXTVAL
         4
<br>
SQL> select seq_test.nextval from dual;
   NEXTVAL
         5
<br>
SQL> shutdown immediate;
Database chiuso.
NOMOUNT del database eseguito.
Istanza ORACLE chiusa.
<br>
SQL> startup
Istanza ORACLE avviata.
<br>
Total System Global Area   47258064 bytes
Fixed Size                   453072 bytes
Variable Size              33554432 bytes
Database Buffers           12582912 bytes
Redo Buffers                 667648 bytes
Database montato.
Database aperto.
<br>
SQL> select seq_test.nextval from dual;
   NEXTVAL
         6
<br>
SQL> select seq_test.nextval from dual;
   NEXTVAL
         7
<br>
SQL> select seq_test.nextval from dual;
   NEXTVAL
         8
<br>
SQL> select seq_test.nextval from dual;
   NEXTVAL
         9
<br>
SQL> shutdown abort
Istanza ORACLE chiusa.
<br>
SQL> startup
Istanza ORACLE avviata.
<br>
Total System Global Area   47258064 bytes
Fixed Size                   453072 bytes
Variable Size              33554432 bytes
Database Buffers           12582912 bytes
Redo Buffers                 667648 bytes
Database montato.
Database aperto.
<br>
SQL> select seq_test.nextval from dual;
   NEXTVAL
      1006Bye, Aron