UPSERT into table with dynamic table name

Question

Any better method to UPSERT into a table, provided :

• Data upsert at ~1 row/second
• Table Name is DYNAMIC, generated using ObjectID parameter passed to

Answer 1

MERGE works perfectly fine with Native dynamic SQL (EXECUTE IMMEDIATE):

create table so_test(pk number not null primary key, value varchar2(20));

insert into so_test(pk, value) values(1, 'one');

declare
  l_SQL varchar2(4000);
  l_tablename varchar2(4000) default 'so_test';
begin
  l_SQL := 'merge into ' || l_tablename || ' target' ||
    ' using (select 1 pk, ''eins'' value from dual union all
             select 2 pk, ''zwei'' value from dual) source
      on (target.pk = source.pk)
      when matched then 
        update set target.value = source.value
      when not matched then
        insert values(source.pk, source.value)      
  ';
  dbms_output.put_line(l_sql);
  execute immediate l_SQL;
end; 

Could you please post the error message you get when using MERGE?

Answer 2

Firstly, you don't have a WHERE in your UPDATE so it will update every row of the table.

Secondly, have you used a mixed case table name. If you do a

CREATE TABLE "testOne" (ID NUMBER);

then the table name will be stored as testOne. But when you do an UPDATE testOne is will be treated as UPDATE TESTONE and you'll get a "no such table" error.

Avoid using mixed case table names. If you absolutely must, then you'll need to quote them in the dynamic SQL statement

Answer 3

You should consider writing this to use Static SQL instead of passing the table name at Run Time. Is there a valid reason why you don't know what table you would be merging into till run-time?

As for debugging the issue...

How is the function FGETTABLENAME defined in your code? This is what I came up with which mimics that scenario. I would suggest Using %type (instead of RAW for Number Types) declarations and removing the Double Quotes from the procedure Names.

    create or replace function FGETTABLENAME(
        POBJECTID in user_objects.object_id%type
    ) return user_objects.object_name%type
    as
      v_object_name user_objects.object_name%type;
    begin
      select object_name
        into v_object_name
        from all_objects
        where object_id = pobjectid;
       return v_object_name;
    end;
    /

SQL> select object_id, object_name from user_objects;

 OBJECT_ID OBJECT_NAME
---------- --------------------------------------------
     52641 TFIVE
     52644 SPINSERTDATA
     52643 PROCEDURE
     52645 FGETTABLENAME
     52554 GET_SAL_EMP
     52559 T1

SQL> select FGETTABLENAME(52641) from dual;

FGETTABLENAME(52641)
--------------------------------------------
TFIVE

You can add DBMS_OUTPUT.PUT_LINE statements to your code after

vTableName := FGETTABLENAME(POBJECTID => pObjectID); 

and 

vQueryUpdate := 'UPDATE '      || vTableName || ' SET "VALUE" = :1';
      vQueryInsert := 'INSERT INTO ' || vTableName || ' ("DTTIME", "VALUE") VALUES (:1, :2)';

or Trace your code to see the actual SQL statements being fired to your Database.