Hi @PmAirtable,

Airtable's single-select field type will force editors to pick from a pre-defined list of values similarly to dropdowns via data validation in Excel.

When pasting data from Excel/elsewhere, Airtable will add any new undefined values to a single-select dropdown field as new options for the field.

There might be a faster way but I frequently follow this process to sanitize data pasted into Airtable:

• Paste values into a grid view with appropriate Airtable field types configured
• Filter on any predefined fields like dropdowns/dates to only show any new strange values or missing dates
• Update records manually with the correctly formatted value
• Finally, when no filtered records are left for strange values, delete the strange option in the field's configuration

It's always best to transform your data as much as possible upstream first before loading into Airtable. You can use the CSV import extension by Airtable in your base to handle these transformations repeatedly as well.

Hope that helps!
-Stephen