Altering Oracle Sequence with result of two subqueries

I am trying to alter a sequence with the result of two subqueries. I am new with Oracle and stuck with a syntax. If you can, please help me with this :

alter sequence COM_UPDN_BASE_FRMT_DTL_SEQ increment by ( (select max(id) from COM_UPDN_BASE_FRMT_DTL) - (select last_number from all_sequences where sequence_name = 'COM_UPDN_BASE_FRMT_DTL_SEQ') ) ;

Upon Executing this, I am getting an "invalid number" error. What am I missing here?

You'll definitely want PL/SQL and dynamic SQL, but don't use LAST_NUMBER.

Try something like this instead:

DECLARE
    l_max NUMBER;
    l_curr_seq_val NUMBER;
    l_new_seq_val NUMBER;
    l_curr_inc_bv number;
BEGIN
    --Get max value from table
    SELECT max(id) INTO l_max FROM COM_UPDN_BASE_FRMT_DTL;
    --get current value from seq and current increment_by from dba_sequences
    SELECT com_updn_base_frmt_dtl_seq.nextval,increment_by INTO l_curr_seq_val,l_curr_inc_bv FROM dba_sequences WHERE sequence_name = 'COM_UPDN_BASE_FRMT_DTL_SEQ' and sequence_owner=USER;
    --If there is a difference, do the fix
    if (l_curr_inc_bv != l_max-l_curr_seq_val) then
        EXECUTE IMMEDIATE
        'ALTER SEQUENCE com_updn_base_frmt_dtl_seq INCREMENT BY ' || (l_max - l_curr_seq_val);
        SELECT com_updn_base_frmt_dtl_seq.nextval INTO l_new_seq_val from dual;
        EXECUTE IMMEDIATE
        'ALTER SEQUENCE com_updn_base_frmt_dtl_seq INCREMENT BY ' || (l_curr_inc_bv);
    end if;
END;
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