Set no duplicate values for form fields

1. Open the form builder.
2. Select the required field.
3. Navigate to the Field Properties > Validation section on the right.
4. Check the No duplicate values checkbox:

   

Once you enable the No duplicate values property, if there are one or more pairs of existing records (submitted through that form) that store the same data in that field, ManageEngine AppCreator will prompt:

Only when you handle these duplicate entries — either by updating them with unique values or nullifying one record from each pair — will ManageEngine AppCreator permit you to enable the No duplicate values property.