Main Page | See live article | Alphabetical index In a relational database, a weak entity is an entity that can't be uniquely identified by its own attributes alone, and therefore must use as its primary key both its own attributes and the primary key of an entity it is related to. A weak entity set is indicated by a bold rectangle (the entity) connected by a bold arrow to a bold diamond (the relationship). This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.