Typically, databases enforce referential integrity by requiring each detail record to point to a valid master record, or NULL. However, PHPMaker does not allow NULL values for master records IDs. I 'd like to request an additional checkbox called "Allow NULL" in the table relations grid.
There are many instances where tables have different relationships depending on the context. For example, table C may be a detail table for both master Table A and master Table B. For certain records, C may be related to A and in other records, C may be related to B. The "Allow Null" option would allow for a null relationship between A and C, while still enforcing referential integrity between B and C, and vice versa.