What is the difference between type and subtype keywords? In some PL SQL example codes, I noticed both usages of type and subtype keywords, each time to declare a custom type (similar to the typedef keyword in C, for example) It seems to me that their u
What is the point of a subtype when a type can be constrained? The question could be where you'd need a type mark that is a named subtype? Qualified expressions for example used to specify the subtype of an aggregate or concatenated expression as a case expression (10 9 Case statement) or in an aggregate assignment from an aggregate expression (e g 10 5 Signal assignment statement)
database - How are super- and subtype relationships in ER diagrams . . . The Information Engineering notation differentiates between inclusive and exclusive subtype relationship IDEF1X notation, on the other hand, doesn't (directly) recognize this difference, but it does differentiate between complete and incomplete subtype (which IE doesn't)
database - Supertype subtype Notation for ERD - Stack Overflow Person Subtype is Non-Exclusive (no Discriminator) Patient Subtype is Exclusive (needs a Discriminator) That is to be used in your code to determine the Subtype, otherwise JOIN to the Subtype Since Resident::Bed is 1::1, the attributes (Bed FK) can be located in Resident This treatment ensures that the Bed that a Patient may be assigned to