Avoiding uniquekey constraint while updating.

Question

hi gurus,
i have the following table with unique constraint on it. i want to update or insert data by avoiding uniquekey constraint(do not disable while doing it).
drop table test_1;
create table test_1
  test1_seq_no  NUMBER not null,
  hdr_id    NUMBER(12) not null,
  rank              NUMBER(4) not null,
  id_versn_cd    VARCHAR2(8)  not null,
  id_seq_no        NUMBER(12) not null,
constraint test_1_uniq unique(hdr_id,rank,id_versn_cd)
insert into test_1 (TEST1_SEQ_NO, HDR_ID, RANK, ID_VERSN_CD, ID_SEQ_NO)
values (1, 121, 1, '9', 111);
insert into test_1 (TEST1_SEQ_NO, HDR_ID, RANK, ID_VERSN_CD, ID_SEQ_NO)
values (2, 121, 2, '9', 112);
insert into test_1 (TEST1_SEQ_NO, HDR_ID, RANK, ID_VERSN_CD, ID_SEQ_NO)
values (3, 121, 3, '9', 113);
insert into test_1 (TEST1_SEQ_NO, HDR_ID, RANK, ID_VERSN_CD, ID_SEQ_NO)
values (4, 121, 4, '9', 114);
commit;
5
1
121
1
9
111
4
2
121
2
9
112
3
3
121
3
9
113
2
4
121
4
9
114
1
5
121
5
9
115
for above example i want to insert new row  with
insert into test_1 (TEST1_SEQ_NO, HDR_ID, RANK, ID_VERSN_CD, ID_SEQ_NO)
values (6, 121, 2, '9', 116);
it should insert new row with rank 2. overriding the old rank.(meaning  id_seq_no 116 should take rank 2) when new rank comes in for id_seq_no 112 our program should update new rank. help is appreciated.

Answer 1

CREATE TABLE "UNIQUE_TEST"
  ( "HDR_ID" NUMBER,
"RANKING" NUMBER,
"ID_VERSN_CD" CHAR(1),
"ID_SEQ_NO" NUMBER,
CONSTRAINT "UNIQUE_TEST_CON" UNIQUE ("HDR_ID", "RANKING", "ID_VERSN_CD") ENABLE
select *
  from unique_test
HDR_ID
RANKING
ID_VERSN_CD
ID_SEQ_NO
121
1
9
111
121
2
9
112
121
3
9
113
121
4
9
114
121
5
9
115
merge into unique_test ut
using (select 121 HDR_ID,2 RANKING,'9' ID_VERSN_CD,116 ID_SEQ_NO
         from dual
       union all
       select HDR_ID,RANKING + 1,ID_VERSN_CD,ID_SEQ_NO
         from unique_test
        where ranking >= (select ranking
                            from (select 121 HDR_ID,2 RANKING,'9' ID_VERSN_CD,116 ID_SEQ_NO
                                    from dual
      ) x
   on (ut.ID_SEQ_NO = x.ID_SEQ_NO)
when matched
then update
         set ut.ranking = x.ranking
when not matched
then insert
      values (x.HDR_ID,x.RANKING,x.ID_VERSN_CD,x.ID_SEQ_NO)
5 row(s) updated.
select *
  from unique_test
order by ranking
HDR_ID
RANKING
ID_VERSN_CD
ID_SEQ_NO
121
1
9
111
121
2
9
116
121
3
9
112
121
4
9
113
121
5
9
114
121
6
9
115
Regards
Etbin