When you select currval , nextval remains unchanged; nextval only changes when you select nextval to get the next value. : Value « Sequences « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Sequences
3. Value

SQL>
SQL> CREATE SEQUENCE test_seq;

Sequence created.

SQL>
SQL> SELECT test_seq.nextval FROM dual;

   NEXTVAL
----------
         1

SQL>
SQL> SELECT test_seq.nextval, test_seq.currval FROM dual;

   NEXTVAL    CURRVAL
---------- ----------
         2          2

SQL>
SQL> SELECT test_seq.nextval, test_seq.currval FROM dual;

   NEXTVAL    CURRVAL
---------- ----------
         3          3

SQL> SELECT test_seq.nextval, test_seq.currval FROM dual;

   NEXTVAL    CURRVAL
---------- ----------
         4          4

SQL>
SQL> SELECT test_seq.nextval, test_seq.currval FROM dual;

   NEXTVAL    CURRVAL
---------- ----------
         5          5

SQL>
SQL> SELECT test_seq.nextval, test_seq.currval FROM dual;

   NEXTVAL    CURRVAL
---------- ----------
         6          6

SQL>
SQL> SELECT test_seq.nextval, test_seq.currval FROM dual;

   NEXTVAL    CURRVAL
---------- ----------
         7          7

SQL>
SQL> drop sequence test_seq
  2  /

Sequence dropped.