A Functional dependency is described by X Y between two groups of attributes Y and X that are subsets of R specifies a constraint on the possible tuple that can make a relation state r of R. The constraint is for any two tuples t2 and t1 in r if t1[X] = t2[X] then they have t1[Y] = t2[Y]. This seems the value of X element of a tuple uniquely calculates the value of element Y.

 

 

Posted Date: 7/30/2012 2:07:19 AM | Location : United States

Ask an Expert

Related Discussions:- What is functional dependency, Assignment Help, Ask Question on What is functional dependency, Get Answer, Expert's Help, What is functional dependency Discussions

Write discussion on What is functional dependency
Your posts are moderated

Write your message here..

Related Questions

Cascading, what is cascading? what is rollback cascading? please explain in... what is cascading? what is rollback cascading? please explain in detail

What is the main advantage of the object model, What is the main advantage ... What is the main advantage of the object model? What are its different components? The object model focuses on the logical data structures. Each object model comprises of many

Keys, #questiontypes of keys examples.. #questiontypes of keys examples..

Fire dementpart, The State of NewYork certifies firefighters throughout sta... The State of NewYork certifies firefighters throughout state and keep track all of them, as well as of the state’s fire departments. Each fire department has unique department numb

Give short note on the following terms- dirty pages and etl, Give short not... Give short note on the following terms:Dirty pages and ETL a.) Dirty pages. These are buffer pages which comprise modifications which haven't been written to disk. b.

Explain th process to avoid re-computation, Saving Derived Attributes to Av... Saving Derived Attributes to Avoid Re-computation Data that is derived from other data should be stored in the computed form to avoid re-computation. For this, we could define

Illustrate the state model for the atm class, Illustrate the State model fo... Illustrate the State model for the ATM class let us take state model for the ATM class given below in Figure showing state model of the ATM class and the pseudo code derived fr

What are the two types of errors, What are the two types of errors? The... What are the two types of errors? The two types of errors are: a) Logical error b) System error

What is the use of sub queries, What is the use of sub queries? A sub q... What is the use of sub queries? A sub query is a select-from-where expression that is nested with in another query. A common use of sub queries is to do tests for set membershi

Decomposition.., explain concept of decomposition? explain concept of decomposition?