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That is, non-key attributes are functionally dependent on the superkey. The set of all attributes is always a superkey (the trivial superkey). Tuples in a relation are by definition unique, with duplicates removed after each operation, so the set of all attributes is always uniquely valued for every tuple.
database of protein similarities computed using FASTA: Protein model databases Swiss-model: server and repository for protein structure models Protein model databases AAindex: database of amino acid indices, amino acid mutation matrices, and pair-wise contact potentials Protein model databases BioGRID: Samuel Lunenfeld Research Institute
Relational database concepts of computer science and Information retrieval concepts of digital libraries are important for understanding biological databases. Biological database design, development, and long-term management is a core area of the discipline of bioinformatics. [3]
A candidate key, or simply a key, of a relational database is any set of columns that have a unique combination of values in each row, with the additional constraint that removing any column could produce duplicate combinations of values. A candidate key is a minimal superkey, [1] i.e., a superkey that does not contain a smaller one. Therefore ...
In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and analyze the data. The DBMS additionally encompasses the core facilities provided to administer the database.
In this example, the three lines next to the song entity indicate that an artist can have many songs. The two vertical lines next to the artist entity indicate songs can only have one performer. In the real world, data modeling is critical because as the data grows voluminous, tables linked by keys must be used to speed up programmed retrieval ...
Additionally it includes the concepts of a subclass and superclass , along with the concepts of specialization and generalization. Furthermore, it introduces the concept of a union type or category, which represents a collection of objects that is the union of objects of different entity types. The EER model also includes EER diagrams that are ...
The advantages of using a natural key to uniquely identify records in a relation include less disk space usage, the natural key is an attribute that is related to the business or the real world so in most cases, it is already being stored in the relation which saves disk space as compared to creating a new column for storing the surrogate key.