Is a Junction-Table basically just the table that sits between two entities that have a M-M relationship?
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A junction table is a weak entity, but a weak entity may be a junction table. A junction table is not the same as a weak entity. A junction table is a type of weak entity. Tables used to resolve repeating groups are also weak entities. These are only junction tables if the repeating group contains a repeated foreign key relationship. |
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Depends how you define a "junction table". ER terminology tends to be somewhat ambiguous when used to describe relational database concepts. A junction table typically means or can mean any table with two or more foreign keys. A weak entity on the other hand is represented by a table whose primary key includes at least one foreign key attribute. That doesn't have to be the case for a junction table (i.e. a table with more than one foreign key). |
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Would it still be considered a "Weak" Entity if the junction table declares its columns with FK constraints and has a composite primary key of those columns? (In other words every row is required to be a valid reference from one table to the other and all such mappings are unique within the junction table). |
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Yes it is. See Wikipedia |
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