How to set current value of a sequence without dropping/recreating

Oracle does not let you change directly the value of a sequence. If you need to change its value, you should re-create the sequence.
On the other hand, we can use a trick to change the value of a sequence without dropping/recreating it.

Let’s say we have a sequence and its value is 1000, and we want to set it to 500.

SQL> CREATE SEQUENCE test_seq

            INCREMENT BY 1

            START WITH 1000

            MINVALUE 1

            MAXVALUE 99999999;

SQL> SELECT last_number

       FROM user_sequences

      WHERE sequence_name = 'TEST_SEQ';

LAST_NUMBER

-----------

1000

SQL> ALTER SEQUENCE test_seq INCREMENT BY -500;

SQL> SELECT test_seq.NEXTVAL FROM dual;

SQL> ALTER SEQUENCE test_seq INCREMENT BY 1;

SQL> SELECT last_number

       FROM   user_sequences

      WHERE  sequence_name = 'TEST_SEQ';

LAST_NUMBER

-----------

500

By this way, we can set the new value of the given sequence.

Just for fun and for easy use of that logic in the future, let’s create a procedure for it.

CREATE OR REPLACE PROCEDURE Set_Sequence_value

              ( pi_owner         IN VARCHAR2,

                pi_seq_name      IN VARCHAR2,

                pi_new_seq_value IN NUMBER)

IS

    PRAGMA AUTONOMOUS_TRANSACTION;

    l_last_number            NUMBER;

    l_incr_by                NUMBER;

    CURSOR c_get_seq_param IS

    SELECT increment_by

      FROM all_sequences

     WHERE sequence_owner = UPPER (pi_owner)

       AND sequence_name = UPPER (pi_seq_name);

BEGIN

    OPEN c_get_seq_param;

    FETCH c_get_seq_param INTO l_incr_by;

    CLOSE c_get_seq_param;

    IF l_incr_by IS NOT NULL

    THEN

        EXECUTE IMMEDIATE 'SELECT '||pi_owner||'.'||pi_seq_name||'.CURRVAL FROM DUAL' INTO l_last_number;

        EXECUTE IMMEDIATE 'ALTER SEQUENCE '||pi_owner||'.'||pi_seq_name||' INCREMENT BY '||(pi_new_seq_value - l_last_number);

        EXECUTE IMMEDIATE 'SELECT '||pi_owner||'.'||pi_seq_name||'.NEXTVAL FROM DUAL' INTO l_last_number;

        EXECUTE IMMEDIATE 'ALTER SEQUENCE '||pi_owner||'.'||pi_seq_name||' INCREMENT BY ' || l_incr_by;

    END IF;

END Set_Sequence_value;

Note: In order to not affect the transaction control, the procedure is created under AUTONOMOUS_TRANSACTION.

Have a fun and thank you for your time to read this article.