Eliminate columns not dependent on key, Database Management System

Assignment Help:

Eliminate Columns Not Dependent On Key

The Employee Relation satisfies -

First normal form - As it has no repeating groups.

Second normal form - As it do not have multi-attribute key.

The employee relation is in 2NF but not 3NF. So we take this table only later than adding the required attributes.

 

Employee Relation

Emp-ID

Emp-Name

Department

Department-Loc

1

Gurpreet Malhotra

A

N-Delhi

2

Faisal Khan

A

N-Delhi

3

Manisha Kukreja

B

Agra

4

Sameer Singh

C

Mumbai

The key is Emp-ID, and the Dept-Name and location defines only about Department, not an Employee. To get the third normal form, they must be moved into a individual relation. Since they define a department, therefore the attribute Department becomes the key of the new "Department" relation.

The motivation for this is the similar for the second normal form: we want not to use or avoid update, insertion and deletion anomalies.;

Department-Relation

Dept-ID

Department

Department Loc

1

A

N-Delhi

2

B

Agra

3

C

Mumbai

 

Employee-List

Emp-ID

Emp-Name

1

Gurpreet Malhotra

2

Faisal Khan

3

Manisha Kukreja

4

Sameer Singh

The rest of the Relation remains similar.

The last two steps: Isolate Semantically Related Multiple Relationships and Isolate Independent Multiple Relationships, changes the relations to higher normal form and are thus not discussed here. They are not even needed for the current example.


Related Discussions:- Eliminate columns not dependent on key

Ordering of tuples, In a relation, tuples are not inserted in any definite ...

In a relation, tuples are not inserted in any definite order. Ordering of tuples is not defined as a part of a relation definition. Though, records may be structured later accordin

Name the three major database in oracle, Name the three major set of files ...

Name the three major set of files on disk that compose a database in Oracle. There are three main sets of files on disk that compose a database. All the files are binary. These

Describe queries with complex types, Describe queries with complex types? ...

Describe queries with complex types? The present extension of the SQL query language deal with the complex type Let us start with the simple example: Find the title and t

What do you mean by correlated subquery, What do you mean by Correlated sub...

What do you mean by Correlated subquery? Subqueries, or nested queries, are used to bring back a set of rows to be used by the parent query. Depending on how the subquery is writ

Benefits and drawbacks of heap files, Benefits of heap files 1.   This i...

Benefits of heap files 1.   This is a easy file Organisation method. 2.   Insertion is somehow capable. 3.   Good for bulk-loading data into a table. 4.   Best if file

What is use of generating such tables, What is use of generating such table...

What is use of generating such tables? How can you create temporary tables? When you require a table only for a short time after that you want it to disappear automatically you

Describe the algorithm for updating indices, Describe the algorithm for upd...

Describe the algorithm for updating indices for a single level index when a record is    (i) Inserted  (ii)  deleted What will be the modification if there are multilevel in

Sorting field groups we cannot use more than one key field, While sorting f...

While sorting field groups we cannot use more than one key field False.

Define the term- control as state within program, Control as State within P...

Control as State within Program 1.  The term control exactly means to check effect of input within a program. For illustration, in Figure, after the ATM card is inserted (a

Explain the advantages of database management system, Advantages of Databas...

Advantages of Database management system Let us summarize the advantages. Reduction of Redundancy: This is perhaps the most important advantage of using DBMS. Redundancy 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