Query of the sequence

Question

Is it possible to change sequence value on monthly basis.
ex. I want to start sequence from 1to 1000 and then reset from 1 to 1000 after month.
for every month i want to reset sequence is it possible.
Thanks in advance

Answer 1

Hi,
I agree with Gj. I think you should use dbms_scheduler to do this at the beginning of every month.
I don't like the idea of dropping and re-creating the sequence. You'll lose grants, and procedures that reference the sequence will become invalid.
You can't alter the actual value of the sequence, but you can temporarily alter the INCREMENT BY value to get the same result, as shown in the script below:
PROMPT     ==========  reset_seq procedure  ==========
CREATE OR REPLACE PROCEDURE     reset_seq
(     in_seq_name     IN     VARCHAR2     -- Name of sequence to be reset
,     in_new_val     IN     NUMBER     := 1     -- Bew value
AUTHID     CURRENT_USER
AS
--     reset_seq changes the value of the given sequence.
--     This assumes:
--       (a) no one else will use the sequence while this is running
--       (b) the INCREMENT BY value of the sequence is 1
--       (c) the MINVALUE value of the sequence is less than in_new_val
--     A little extra coding can fix (b) and (c)
     current_val     PLS_INTEGER;
     get_txt     VARCHAR2 (1000)     := 'SELECT ' || in_seq_name || '.NEXTVAL'
                    || '     FROM dual';
     set_txt VARCHAR2 (1000)     := 'ALTER SEQUENCE ' || in_seq_name
                    || '     INCREMENT BY ';
BEGIN
     EXECUTE IMMEDIATE get_txt INTO current_val;
     EXECUTE IMMEDIATE set_txt || TO_CHAR (FLOOR ((in_new_val - 1) - current_val));
     EXECUTE IMMEDIATE get_txt INTO current_val;
     EXECUTE IMMEDIATE set_txt || '1';
END     reset_seq
SHOW ERRORS
PROMPT     ==========  Creating sequence  ==========
DROP SEQUENCE     x_seq;
CREATE SEQUENCE     x_seq
MINVALUE     0
NOCACHE
START WITH     1;
PROMPT     ==========  Using some values  ==========
SELECT     x_seq.NEXTVAL
FROM     dual
CONNECT BY     LEVEL     <= 5;
PROMPT     ==========  Re-setting sequence  ==========
EXECUTE     reset_seq ('x_seq');
SELECT     x_seq.NEXTVAL     AS new_improved
FROM     dual;The first two steps (creating the reset_seq procedure and creating the sequence) are done once, for all time.
The next step "using some value" simulates your normal work during the month.
At the beginning of every month, call reset_seq, as shown.