Entering check values into the check flags of a relation has the effect that DataView checks the number of dependent master elements if the user wants to delete a selected parent- or child record in one of the connected tables. If the record to be deleted has dependent master elements, DataView will only allow the delete operation if the number of dependent records is smaller than the check value entered in the check flag. If this is the case, the selected parent- or child record can be deleted by the user.
For the different relations the following check flags exist:
Depending on the relation the entries in the check flags have the following effects:
Please note that the check flag procedure is functionally connected with the standard procedure for securing referential integrity without any user activities required. If deleting master tables is allowed, DataView will automatically delete the connected relation- or type records.
Example: In the meditronic application a user is to be only allowed an item from the item master if the item is provided by less than three suppliers. This is defined by the check flag entry >Ch = 3 in the refine relation Item-Supplier. As displayed in the figure DataView will check the number of suppliers. For there are only two of them, the item can be deleted. The standard procedure for securing referential integrity will then automatically delete the relation records which are no longer needed.