With the combination fields, you can either save the value of a field in a database or display this value in a form.
The user values entered in the combination field or selected in the list can be saved in the database table that is accessed in the form. Note that the saving of values in another table is not possible. If the values are not to be saved in a database, they will be saved only in the form. This is especially helpful in HTML forms, where the user's entered or selected values are to be assigned to a server.
Two options are available for this question:
Specifies whether the user's entered or selected combination field value should be saved in a database field. Several database table fields are offered which can be accessed in the current form.
In Control - Properties the selected field appears as an entry in the Data tab page under Data field.
Specifies the data field where the combination field value should be saved.
Specifies that the value of this combination field will not be written in the database and will only be saved in the form.