Changing a Single-Table Implementation into a Multiple-Subtypes Implementation

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You cannot change an existing single-table implementation (e.g. one big Persons table) into a multiple-subtypes implementation (e.g. a Persons supertype with Male and Female subtypes) without penalties if you set one of the subtype indicator columns to mandatory, with a default values of Yes. In such a situation, USoft Developer expects every supertype record to have a subtype record. The subtype records would be mandatory but would not yet exist. Opening the subtype window involved would result in error messages, because USoft Developer tries to lock the non-existing subtype record.

A similar situation will occur if you specify a Totality rule in an existing situation. In this case, too, subtype records will be assumed to be in the database.