How can I change multiple records using Data Import?
Data Import Wizard
Oracle Service Cloud, All versions
If you need to make changes on multiple records, you can use the Data Import Wizard feature in order to change the value of one or more fields (even custom fields). For example, if you create a custom field which is menu type and after a while, you decide to modify this for some contacts, you can use Data Import wizard and set this field to another value.
Please keep in mind that a record cannot be modified set to Null value via Data Import Wizard, which means that if you choose "No value" or "empty space" for a field, this will be ignored on the data import process. As an alternative for nullifying a field, you can use a report with Inline editing or multi-edit workspace.
For more information, refer to Answer ID 4191: What is the Data Import feature?