insert if not exists oracle

Question

I need to be able to run an Oracle query which goes to insert a number of rows, but it also checks to see if a primary key exists and if it does, then it skips that insert.

Answer 1

This is an answer to the comment posted by erikkallen:

You don't need a temp table. If you only have a few rows, (SELECT 1 FROM dual UNION SELECT 2 FROM dual) will do. Why would your example give ORA-0001? Wouldn't merge take the update lock on the index key and not continue until Sess1 has either committed or rolled back? – erikkallen

Well, try it yourself and tell me whether you get the same error or not:

SESS1:

create table t1 (pk int primary key, i int);
create table t11 (pk int primary key, i int);
insert into t1 values(1, 1);
insert into t11 values(2, 21);
insert into t11 values(3, 31);
commit;

SESS2: insert into t1 values(2, 2);

SESS1:

MERGE INTO t1 d
USING t11 s ON (d.pk = s.pk)
WHEN NOT MATCHED THEN INSERT (d.pk, d.i) VALUES (s.pk, s.i);

SESS2: commit;

SESS1: ORA-00001

Answer 2

We can combine the DUAL and NOT EXISTS to archive your requirement:

INSERT INTO schema.myFoo ( 
    primary_key, value1, value2
) 
SELECT
    'bar', 'baz', 'bat' 
FROM DUAL
WHERE NOT EXISTS (
    SELECT 1 
    FROM schema.myFoo
    WHERE primary_key = 'bar'
);

Answer 3

INSERT INTO schema.myFoo ( primary_key        , value1          , value2         )
                         SELECT 'bar1' AS primary_key ,'baz1' AS value1 ,'bat1' AS value2 FROM DUAL WHERE (SELECT 1 AS value FROM schema.myFoo WHERE LOWER(primary_key) ='bar1' AND ROWNUM=1) is null;

Answer 4

If your table is "independent" from others (I mean, it will not trigger a cascade delete or will not set any foreign keys relations to null), a nice trick could be to first DELETE the row and then INSERT it again. It could go like this:

DELETE FROM MyTable WHERE prop1 = 'aaa'; //assuming it will select at most one row!

INSERT INTO MyTable (prop1, ...) VALUES ('aaa', ...);

If your are deleting something which does not exist, nothing will happen.

Answer 5

DECLARE
   tmp NUMBER(3,1);
BEGIN
  SELECT COUNT(content_id) INTO tmp FROM contents WHERE (condition);
  if tmp != 0 then
    INSERT INTO contents VALUES (...);
  else
    INSERT INTO contents VALUES (...);
  end if;
END;

I used the code above. It is long, but, simple and worked for me. Similar, to Micheal's code.

Answer 6

Coming late to the party, but...

With oracle 11.2.0.1 there is a semantic hint that can do this: IGNORE_ROW_ON_DUPKEY_INDEX

Example:

insert /*+ IGNORE_ROW_ON_DUPKEY_INDEX(customer_orders,pk_customer_orders) */
  into customer_orders
       (order_id, customer, product)
values (    1234,     9876,  'K598')
     ;

---

UPDATE: Although this hint works (if you spell it correctly), there are better approaches which don't require Oracle 11R2:

First approach—direct translation of above semantic hint:

begin
  insert into customer_orders
         (order_id, customer, product)
  values (    1234,     9876,  'K698')
  ;
  commit;
exception
  when DUP_VAL_ON_INDEX
  then ROLLBACK;
end;

Second aproach—a lot faster than both above hints when there's a lot of contention:

begin
    select count (*)
    into   l_is_matching_row
    from   customer_orders
    where  order_id = 1234
    ;

    if (l_is_matching_row = 0)
    then
      insert into customer_orders
             (order_id, customer, product)
      values (    1234,     9876,  'K698')
      ;
      commit;
    end if;
exception
  when DUP_VAL_ON_INDEX
  then ROLLBACK;
end;