| # Possible values Child will be updated All children that refer to the parent will be updated. Note If the reference does not identify the relation this may result in the automatic update of many records. For example if the relation between the parent and the child is not one-to-one but one-to-many. Restricted (with counter) Any change of the primary key fields of the parent is not allowed if any child refers to this record. A reference counter is checked, which indicates how many children refer to the parent. With each database action this counter will be checked and updated, if necessary. Nullifies The field(s) of the child, which refer(s) to the updated parent record, will be made empty (spaces or zero values). No check If the parent is changed, no check or action will be done on the child records which refer to the parent. In that case the referential integrity of the database cannot be guaranteed. Lookup (Restricted) Any change of the primary key fields of the parent is not allowed if any child refers to this record. |