When creating lookup fields, you can configure the lookup relationship so that when you are creating records, the selection of the lookup is either mandatory or optional. If it is set to optional, the following three options are available to specify which choice of actions are to be carried out if the lookup record is subsequently deleted:
- The Clear the value of this field option is the default choice
- The Don't allow deletion of the lookup record that's part of a lookup relationship option doesn't allow deletion of the lookup record that's part of a lookup relationship
- The Delete this record also option is shown only for lookups to custom objects
These three options are explained in the next section.
