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Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 24. Chapters: Component-oriented database, Database model, Entity-attribute-value model, Flat file database, Graph database, Hierarchical database model, Network model, Object-relational database, Object database, Semi-structured model. Excerpt: Entity-attribute-value model (EAV) is a data model to describe entities where the number of attributes (properties, parameters) that can be used to describe them is potentially vast, but the number that will actually apply to a given entity is relatively modest. In mathematics, this model is known as a sparse matrix. EAV is also known as object-attribute-value model, vertical database model and open schema. There are certain cases where an EAV schematic is an optimal approach to data modelling for a problem domain. However, in many cases where data can be modelled in statically relational terms an EAV based approach is an anti-pattern which can lead to longer development times, poor use of database resources and more complex queries when compared to a relationally-modelled data schema. This data representation is analogous to space-efficient methods of storing a sparse matrix, where only non-empty values are stored. In an EAV data model, each attribute-value pair is a fact describing an entity, and a row in an EAV table stores a single fact. EAV tables are often described as "long and skinny" "long" refers to the number of rows, "skinny" to the few columns. Data is recorded as three columns: One example of EAV modeling in production databases is seen with the clinical findings (past history, present complaints, physical examination, lab tests, special investigations, diagnoses) that can apply to a patient. Across all specialities of medicine, these can range in the hundreds of thousands (with new tests being developed every month). The majority of individuals who visit a...