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The chase is a simple fixed-point algorithm testing and enforcing implication of data dependencies in database systems. It plays important roles in database theory as well as in practice. It is used, directly or indirectly, on an everyday basis by people who design databases, and it is used in commercial systems to reason about the consistency ...
Thus, it is important to test in order to obtain a database system which satisfies the ACID properties (Atomicity, Consistency, Isolation, and Durability) of a database management system. [ 1 ] One of the most critical layers is the data access layer, which deals with databases directly during the communication process.
For example, consider a database of electronic health records. Such a database could contain tables like the following: A doctor table with information about physicians. A patient table for medical subjects undergoing treatment. An appointment table with an entry for each hospital visit. Natural relationships exist between these entities:
In database theory, the CAP theorem, also named Brewer's theorem after computer scientist Eric Brewer, states that any distributed data store can provide only two of the following three guarantees: [1] [2] [3]
A logical data model or logical schema is a data model of a specific problem domain expressed independently of a particular database management product or storage technology (physical data model) but in terms of data structures such as relational tables and columns, object-oriented classes, or XML tags.
Codd's twelve rules [1] are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases, designed to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS).
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First normal form (1NF) is a property of a relation in a relational database.A relation is in first normal form if and only if no attribute domain has relations as elements. [1]