Oracle 21c

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CREATE SEQUENCE e_demo2_tab_sq;
CREATE TABLE e_demo2_tab 
(
    tab_id   NUMBER(10) DEFAULT e_demo2_tab_sq.nextval NOT NULL,
    e_id     NUMBER(10),
    e_uuid   NUMBER(10),
    seq_cnt  NUMBER(10)
);
INSERT INTO e_demo2_tab VALUES(e_demo2_tab_sq.nextval, 11, 13, null);
1 rows affected

INSERT INTO e_demo2_tab VALUES(e_demo2_tab_sq.nextval, 11, 13, null);
1 rows affected

INSERT INTO e_demo2_tab VALUES(e_demo2_tab_sq.nextval, 11, 16, null);
1 rows affected

INSERT INTO e_demo2_tab VALUES(e_demo2_tab_sq.nextval, 11, 15, null);
1 rows affected

INSERT INTO e_demo2_tab VALUES(e_demo2_tab_sq.nextval, 11, 14, null);
1 rows affected

INSERT INTO e_demo2_tab VALUES(e_demo2_tab_sq.nextval, 11, 14, null);
1 rows affected

INSERT INTO e_demo2_tab VALUES(e_demo2_tab_sq.nextval, 11, 15, null);
1 rows affected

INSERT INTO e_demo2_tab VALUES(e_demo2_tab_sq.nextval, 11, 16, null);
1 rows affected

select * from e_demo2_tab order by tab_id;


TAB_ID
E_ID
E_UUID
SEQ_CNT


1
11
13
null

2
11
13
null

3
11
16
null

4
11
15
null

5
11
14
null

6
11
14
null

7
11
15
null

8
11
16
null


merge into e_demo2_tab a
      using (select
               rowid rid,
               row_number() over (partition by e_id, ceil(e_uuid/2) order by e_uuid, rowid) rn
             from e_demo2_tab) x
    on (a.rowid = x.rid)
    when matched then update set a.seq_cnt = x.rn;
8 rows affected

select * from e_demo2_tab order by tab_id;


TAB_ID
E_ID
E_UUID
SEQ_CNT


1
11
13
1

2
11
13
2

3
11
16
3

4
11
15
1

5
11
14
3

6
11
14
4

7
11
15
2

8
11
16
4

TAB_ID	E_ID	E_UUID	SEQ_CNT
1	11	13	null
2	11	13	null
3	11	16	null
4	11	15	null
5	11	14	null
6	11	14	null
7	11	15	null
8	11	16	null