A SQL statement that updates a column requires access rights on the table to which the column belongs, except in the following situations:
If the column is part of the primary key of a subtype constellation, the UPDATE right is checked only in the uppermost supertype table. Any rights defined (for the column) on subtype tables are ignored.
If the column is a subtype indicator column that is switched from 'Y' to 'N', this causes the subtype data to be deleted (if the subtype object data is physically stored in a separate table), and the supertype record to be updated (its subtype indicator column is set to N).
However, denying the delete right on the subtype table is not enough to prevent loss of the subtype object data. This may appear confusing, but an UPDATE of the subtype indicator column is also considered to be an UPDATE on the subtype table. In this situation, an UPDATE right on the subtype is sufficient for the user to be able to delete the subtype record: DELETE is not required.
Likewise, if the column is a subtype indicator that is switched from 'N' to 'Y', this is considered to be an update on the supertype and subtype tables. UPDATE rights at the supertype and subtype levels is sufficient for the user to be able to add the subtype record: INSERT is not required.
The differences between manipulation types in subtype constellations can be slight. If the subtype is physically stored in a separate table, when you add a new supertype with the subtype indicator set to 'Y', this causes both a subtype and supertype record to be inserted at Store Record time. If, for whatever reason, the Store Record event executes before the subtype columns are populated, for example immediately after selecting the subtype indicator in the supertype box, and before navigating to the subtype box, then populating the subtype columns, again followed by a Store Record event, corresponds to an UPDATE of the supertype in addition to the INSERT.