Referential integrity, Database Management System

Assignment Help:

It can be easily defined as:

The database must not have any unmatched foreign key values.

The term "unmatched foreign key value" means a foreign key value for which there does not exist a matching value of the relevant candidate key in the relevant target (referenced) relation. For instance, any value existing in the EMPID attribute in ASSIGNMENT relation must be in the EMPLOYEE relation. That is, the only EMPIDs that can be in the EMPLOYEE relation are 101, 102 and 103 for the instance / present state of the database given in Figure. If we want to insert a tuple with EMPID value 104 in the ASSIGNMENT relation, it will cause violation of referential integrity constraint. Logically it is very obvious after all the employee 104 does not be, so how can s/he be assigned any work.


Related Discussions:- Referential integrity

Backward recovery (undo), Backward Recovery (UNDO): In this system the unco...

Backward Recovery (UNDO): In this system the uncommitted changes made by a transaction to a database are undone.  Instead the system is reset to the last consistent state of databa

Sequential file organisation, Sequential File Organisation The most nec...

Sequential File Organisation The most necessary way to organise the collection of records in a file is to use sequential Organisation. Records of the file are stored in series

State the design of associations, State the Design of Associations Bef...

State the Design of Associations Before designing associations, it is essential to know the way they are used. For this, analysis of association traversals is required. It is

Develop a cards website, Project Description: I want to build a card pla...

Project Description: I want to build a card playing Website. The user should be able to 1. Login. 2. Have profile access. 3. Put money into the site. 4. Selects t

ENTITY DIAGRAMS IN FIRST NORMAL FORM, CAN SOMEONE HELP ME WITH ENTITY DIAGR...

CAN SOMEONE HELP ME WITH ENTITY DIAGRAMS IN FIRST NORMAL FORM?

Architectural standard, Architectural standard: Designation : Archit...

Architectural standard: Designation : Architect , Consultant Job Profile : As a part of Oracle Fusion Middleware at Satyam, I am involved with Presales, Delivery, A

Database schema, #Use the following database schema: 1) Patient—PatientID, ...

#Use the following database schema: 1) Patient—PatientID, Name, DOB 2) Doctor—DoctorID, Name, MedLicenseNumber, Phone 3) Medication—MedicationID, BrandName, GenericName 4) Prescrip

What are the dbms languages, What are the DBMS languages? Briefly explain?...

What are the DBMS languages? Briefly explain? Data Definition language (DDL):A database schema is specified through a set of definitions expressed through a special language

Single-valued dependencies, Single-Valued Dependencies A database is a ...

Single-Valued Dependencies A database is a collection of related information and it is therefore inevitable that some items of information in the database would depend on some

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