Data Loader Actions: Insert Loads data from a data source into Salesforce as new records.
Update Loads data from a data source into Salesforce, where existing records with matching ID fields are updated.
Upsert Loads data from a data source into Salesforce, where existing records with a matching custom external ID field are updated; records without matches are inserted as new records.
Delete Loads data from a data source into Salesforce, where existing records with matching ID fields are deleted
To perform Update operation you will need to have ID field.
In dataloader, Id is not required for Insert operation.
Can you describe the scenario for updation of records.
Thanks,
Pratik
You can do upsert using external id.
You can refer this:
http://www.salesforce.com/us/developer/docs/dataLoader/Content/inserting_updating_or_deleting_data.htm
Thanks,
Pratik
P.S. If this answers you question, please mark it as "Best Answer" so it will help other community members too.
Data Loader Actions:
Insert
Loads data from a data source into Salesforce as new records.
Update
Loads data from a data source into Salesforce, where existing records with matching ID fields are updated.
Upsert
Loads data from a data source into Salesforce, where existing records with a matching custom external ID field are updated; records
without matches are inserted as new records.
Delete
Loads data from a data source into Salesforce, where existing records with matching ID fields are deleted
Thnaks,
Pratik