Assume Unique Identifiers Page
In the Advanced Options window, the Assume Unique Identifiers page displays Assume unique identifiers. This checkbox indicates whether identifiers must be unique for the records being imported.
For this page to be shown, all of the following conditions must be met:
• An identifier field is being imported.
• records are being added or, if records are being updated, Allow new records to be added during update is selected on the Select Import Type page.
• The source file is a Microsoft Access or Microsoft Excel file. When the source file is a text file, this page is not shown.
You should select the checkbox on this page only if you are importing identifiers that you know do not already exist in the open file. When this checkbox is selected, the identifiers in the source file are checked for uniqueness before the import begins. If the identifiers are not unique, an error is shown.