Earlier this week I uploaded a large list. Aside from email address, columns in the list included Revenue and Number of Employee fields. This was an effort to append our database with updated demographic information. What I did not realize is that a good portion of the contacts in the list had nothing in those fields. My question is as follows:
If I upload a list and one of the fields I upload is empty (not "NULL", but completely blank), will that overwrite data that may have already been in Marketo? If a contact did have something in the "Annual Revenue" field, and in the file I uploaded, that same contact had an empty field, would that empty value overwrite the pre-existing data? My hope is that data will only be overwritten in a list upload if the field said "NULL".
An empty value in a list import should not overwrite a field if there is already a value there. You can check this though, by using a smart list to find those leads who are both a member of your imported list, and who have had data value changes to those fields.