Implementing a Mutually Exclusive Relationship in the Database | Oracle All Things SQL Blog
The relationship with either entity is formed using the same "foreign key" . UPDATE, or DELETE statement can be defined on a table or view. Data Analytics and Data Management>SQL Server Keywords that define a product are prime examples of this condition. In a mutually exclusive structure, an entity falls into no more than one subtype category. to a 1:M relationship; the overlapping supertype-subtype is more like an M:N relationship. The developer may have to learn SQL three-valued logic if boolean tests are done on nullable columns. This can be baffling at first, but one.
Должно быть что-то самое простое.
How to model a mutually exclusive relationship in SQL Server - Stack Overflow
Техник в оперативном штабе начал отсчет: - Пять. Четыре. Три.