Fds in relationships and teaches relationship, Database Management System

FDs in Relationships:

 Enrols Relationship: None as it is many to many

Teaches Relationship: Course code → Instructor

Instructor → Course code

The next question is:  How do we recognize the functional dependence in a database model?

Functional dependencies occur from the nature of the actual world that the database models. Often A and B are facts about an entity where A may be some identifier for the entity and B some characteristic. Functional dependencies cannot be automatically determined by studying one or more cases of a database. They can be determined only by a careful study of the actual world and a clear understanding of what every attribute means.

 There are no thumb rules for determining FDs.

Functional dependence is an vital concept and a large body of formal theory has been developed about it.

 

Posted Date: 3/7/2013 1:54:10 AM | Location : United States







Related Discussions:- Fds in relationships and teaches relationship, Assignment Help, Ask Question on Fds in relationships and teaches relationship, Get Answer, Expert's Help, Fds in relationships and teaches relationship Discussions

Write discussion on Fds in relationships and teaches relationship
Your posts are moderated
Related Questions
#quesDefine a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a pi

Speedup Query Processing: A query that includes data at various sites can be split into sub-queries. These sub- queries can be implemented in parallel by various sites. Such parall

Properties of a Transaction        A transaction has four main properties. These are: Atomicity Consistency Isolation or Independence Durability or Permanen

Exclusive lock It is asked for by a transaction on a data item that it wants to update. No other transaction can put either a shared lock or an exclusive lock on a dat

Discuss the differences among the candidate keys and the primary key of a relation. Give instance to describe your answer? A candidate key is one that can be used as primary ke

Consider the relations EMP(ENO,ENAME,AGE,BASIC_SALARY) WORK_IN(ENO,DNO) DEPT(DNO,DNAME,CITY) Express the following queries in SQL (i) Find names of employees who work in a dep

How to create values of structured type? Constructor functions are used to make values of structured types. A function with the similar name as a structured type is a construct

Consider the relations described below: PHYSICIAN (regno, name, telno, city) PATIENT (pname, street, city) VISIT (pname, regno, date_of_visit, fee) Where the regno and pname ide

Describe the candidate key functions ? Candidate Key and Alternate Key: In some instances, an entity will have more than one attribute which can serve as a primary key. Any key

What is an Index? An index is a small table having only two columns. The first column has a copy of the primary or candidate key of a table and the second column having a set o