Hi Egemen,
In your case use MODIFY instead of INSERT.
basic difference between INSERT, UPDATE & MODIFY --
INSERT: when new record has to inserted into table.
UPDATE: When record in present in table & need to be change.
MODIFY: this combination of both Insert & Update, means if record is not present it will add the record into table otherwise it will update the existing record without inserting again.
For more information check these link.
Regards,
Jyoti