6. Which of the following is a type of functional dependency? Trivial Functional Dependency Non-trivial Functional Dependency Both A and B None of the above Answer:C) Both A and B Explanation: There are mainly four types of Functional Dependency in DBMS: ...
What are Armstrong's Axioms in Functional Dependency in DBMS?Armstrong axioms are a complete set of inference rules or axioms, introduced and developed by William W. Armstrong in 1974. The inference rules are sound which is used to test logical inferences of functional dependencies. The axiom ...
The dependency of an attribute on a set of attributes is known as trivial functional dependency if the set of attributes includes that attribute. Symbolically: A ->B is trivial functional dependency if B is a subset of A. The following dependencies are also trivial: A->A & B->B For exam...
Functional dependency (FD) is an important data dependency. Due to the nature of software development and maintenance and the limitation of database management system (DBMS) in handling FD enforcement, many functional dependencies are enforced in the transactions that update the database, but not ...
AfunctionaldependencyXYisnon-trivial(非平凡函数依赖)ifYX= {supervisor_id}{specialization} Non-trivialFDsaregivenimplicitlyintheformofconstraintswhendesigningadatabase. Forinstance,thespecializationofastudentsmustbethesameasthatofthesupervisor. ...
Starting from SQL-99, the concept of “functional dependency” was introduced; a column B is functionally dependent on columns {A1, A2} in a result set if all rows which share the same value of A1 and the same value of A2 necessarily share the same value of B. Then ...
data redundancy/ C6130D Document processing techniques C6160 Database management systems (DBMS)According to the analysis of existing complicated functional dependencies constraint,we conclude the conditions of defining functional dependency in XML,and then we introduce the concept of the node value ...
(An example of an inclusion dependency is the sentence that says that every MANAGER is an EMPLOYEE.) If, however, the sentences of interest are inclusion dependencies and unrestricted functional dependencies, then there need not exist an Armstrong database. This result holds even if we allow ...
DBMSmultivalued dependenciesjoin dependenciesworst case running timelossless join dependenciesacyclic join dependencieshierarchical decompositionsfunctional dependenciespolynomial/ C6160D Relational databasesWe describe an algorithm to test whether a multivalued dependency is implied by a set of functional and join...
List of DBMS Functional Dependencies Aptitude Questions and Answers 1)Functional Dependencyis? Set of constrains between two attributes in a relation. Set of constrains between two tuples in a relation. Both 1 and 2. None of these. Answer ...