Define transitive dependencies, Database Management System

Assignment Help:

What do you understand by transitive dependencies? Define with an example any two problems that can take place in the database if transitive dependencies are available in the database.

 Ans:  Assume X, Y, and Z are the set of attributes. If X → Y and Y → Z afterwards the functional dependency X → Z is a transitive functional dependency. Alternatively, if a nonkey attribute is as well functionally dependent on the other nonkey attribute(s), then there is a transitive functional dependency. Transitive functional dependencies are as well cause the data redundancies and the other consequences. For instance, consider the subsequent relation:

CREATE TABLE CONTACTS

(CONTACT_ID NUMBER (5) PRIMARY KEY,

 L_NAME   VARCHAR (20),

 F_NAME   VARCHAR (20),

 COMPANY_NAME VARCHAR (20),

 COMPANY_LOCATION VARCHAR (50))

 In the following relation, all the nonkey attributes are functionally dependent on the primary key, that is CONTACT_ID. But, there is as well a transitive functional dependency exists in the relation - CONTACT_ID  COMPANY_LOCATION because CONTACT_ID → COMPANY_NAME and COMPANY_NAME →COMPANY_LOCATION.  The result of transitive dependency, there are anomalies in the above relation like this:

  • Insertion Anomaly - A new company cannot be inserted till a contact person has been assigned to that company.
  • Deletion Anomaly - If a company has just only one contact person and is deleted from the table, we will lose the information about that company, as the company information is related with that person.
  • Update Anomaly - If a company changes its location we will should make the changes in all the records in which the company name appears.

Related Discussions:- Define transitive dependencies

Computing the closure of a set of functional dependency, What is meant by c...

What is meant by computing the closure of a set of functional dependency? The closure of F denoted by F + is the set of functional dependencies logically implied by F.

What are axioms, What are axioms? Axioms or rules of inference give a s...

What are axioms? Axioms or rules of inference give a simpler technique for reasoning about

Explain the togaf framework for enterprise architectures, Question: (a)...

Question: (a) With the help of a diagram, explain the TOGAF framework for enterprise architectures. (b) Where would you position enterprise architectures in an enterpri

Define the normalisation form, Define in which normalisation form if an att...

Define in which normalisation form if an attribute of a composite key is dependent on an attribute of other composite key. Ans: 3NF A relation is in 3 NF if an attribute of

Create a table student with attributes student name, Question 1 Create a t...

Question 1 Create a table student with attributes student name, roll number, total marks and percentage. Do the following operations Insert details in to the table Update

How are tables stored on disk?, How are tables stored on Disk? We reali...

How are tables stored on Disk? We realise that every record of a table can have different amounts of data. This is due to in some records; some attribute values may be "zero".

Problems of concurrent transactions-lost updates, Lost Updates : Suppose th...

Lost Updates : Suppose the two transactions T3 and T4 run simultaneously and they happen to be interleaved in the following way (suppose the initial value of X as 10000):

Modelling and normalisation, Task Part A. Create an ERD from a business pro...

Task Part A. Create an ERD from a business problem. (50 marks) Read the following problem and complete the tasks listed below. THE ABS Blood Bank Australian Blood Services (ABS) i

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd