Unlike SQL INSERT statements, SQL UPDATE statements do not create records. Therefore, the problems that the Relativity DBMS faces for an INSERT operation do not apply. As a general rule, the Relativity DBMS allows any table to be updated if the user marks it updatable in the Relativity Designer using the Allow Updates check box on the Table Form toolbar. Some restrictions on the columns that can be updated, however, do apply.
In particular, the Relativity DBMS allows updates to tables that contain columns defined on repeating data items. Note that such tables contain two sorts of columns:
Therefore, an update to the latter sort of column would change multiple rows. The Relativity DBMS does not permit updates to the latter sort of column in such a table.
Hence, if a record contains both repeating and nonrepeating data items, the Relativity DBMS allows the user to update the nonrepeating data items via a table that has no columns defined on repeating data items, or to update the repeating data items via a table that has repeating data.
For more information on the rules that apply to updating existing records, see Update Rules.