Relational database normalization is the process of decomposing relations with anomalies to produce well structured relations. This paper delves into relational database normalization giving the reason why a database schema in third normal form is considered to be of higher quality than an un-normalized database schema.
Relational database normalization entails organizing database and it includes the creation of tables as well as relationships establishment between the tables using designed rules intended to protect the data as well as make the database to be flexible. This is achieved through the elimination of redundancy as well as inconsistent dependency. Redundant data is known to waste the space of the disk thereby creating problems of
…show more content…
It also helps in maintaining data consistency in the database. The purpose of normalization is therefore to avoid redundancy by storing each fact within the database only once, to put data into the form that is more able to accurately accommodate change, to avoid certain updating anomalies, to facilitate the enforcement of data constraint and to avoid unnecessary coding. Extra programming in triggers stored procedures can be required to handle the non-normalized data and in turn can impair performance significantly (Davidson & Moss, 2012).
The degree of normalization is defined by normal forms. The forms in an increasing level of normalization include first normal form (1NF), second normal form (2NF), third normal form (3NF), Boyce-Codd normal form, Fourth normal form (4NF) and fifth normal form (5NF).Each normal form is a set of conditions on schema that guarantees certain properties relating to redundancy and update anomalies. In certain instances of lower level of normalization, queries take time to execute (Colomb,
…show more content…
In this second normal form level, deficiencies which are transitive are removed. Third normal form satisfies the condition which requires that the relation to be in the second normal form. Another condition that it full is that it must not have transitive dependencies within the relations in the database. Transitive dependency occurs if an attribute is found to be functionally dependent on the key in an indirect manner. In this level, remaining functional dependency anomalies is removed. Boyce-Codd Normal requires that the relation to be in third normal form and that every determinant is supposed to be a candidate key. In this level, multi-valued dependencies are removed. A relation is in fourth normal form is it has a composite key and its key attributes have no multi-valued dependencies. In the fourth normal form, the remaining anomalies are removed. Fifth normal form is a generalization of the fourth normal form. It states that if a relation can be decomposed into the lossless join of several relations, then it should be so decomposed. The fifth normal form concerns dependencies that are obscure (Colomb, R. (2003)
A database schema in third normal form is considered to be of higher quality than an un-normalized database schema because the third normal form ensures that
* Write clearly and concisely about relational database management systems using proper writing mechanics and technical style conventions.
A relational database is a database that consists of a collection of tables with columns showing entities, and rows showing data. This type of database uses a primary key and foreign key. The foreign key in another table will point to the primary key of a table, and this is how tables can relate to each other. This permits for one-to-one, one-to-many, and many-to-many relationship between the data. An advantage of relational databases includes the ease of adding or modifying new tables and entities without needing to change the structure of the database already in place. Relational database have many features, including indexing, setting data type, and setting validation tests, all these help to ensure data integrity.
To answer each question, darken the circle corresponding to your answer using a pencil. If you decide to change your answer, please erase your original answer completely and darken your new answer.
This week was a little harder comparing to last; well it is expected because we are getting more into how to create a more dependable database. The topics for this week were “The problem of redundancy, Decompositions, Functional Dependencies and normal forms. We learned how to recognize and avoid the problem redundancy in database along with how to convert database schema into first, second, third normal forms.
There are three stages to normalization, 1st NF, 2nd NF, and 3rd NF. In the 1st NF stage must ensure that the table has no multivalued attributes. If there are the table should be broken down into separate tables so that there are no multivalued attributes. The 2nd NF stage requires that we break the tables down even more to ensure that all attributes and functional dependency entirely to the primary key and has met all requirements of the 1st NF. Then, and only then will it be considered to have met 2nd NF requirements. To transform the database to 3rd NF you must identify the primary key in the 2nd NF table. Then we must identify functional dependencies in the relationship to ensure there are no transitive dependencies. These types of dependencies can cause insertion, deletion, and update
Hence, this session has enhanced my understanding about normalization and how essential to create a data that is well organized with the relationships clearly defined and established between the tables (based on the business rules) in order to eliminate data redundancy and inconsistency.
2NF (Second Normal Form): The relation should not have any partial dependencies; part of the primary key should not identify a subset of attributes in the same table. The relation must be in 1NF before it can be in 2NF [12]
Spellman University had requested that I develop a database for their college. The purpose of the database will be to track the students and the courses. There also will be a place in the system to track the instructors teaching each course. There are many things to be considered in composing this database. This paper will outline the entities, attributes for each entity, the type of relationship, constraints, some business rules, and the conceptual and physical models.
First our team will talk about how Microsoft Access was used to create these tables by Huffman Trucking Database. Then how we used the tables with made up information to be tested on. Then on how we used forms in the maintenance database system. While the creation of relationships and normalization is explained in the process of using queries to search the database (University of Phoenix, 2007).
Except where indicated, use MySQL Query Browser to perform each operation and print the results.
Data normalization is a process by which large tables are divided into smaller tables, and then relationships are defined between them. These relationships could be one-to-one, one-to-many, or many-to-many. The idea behind normalization is to eliminate redundant information and avoid data anomalies that could compromise the integrity of your data. Additionally, you can reduce the amount of space your database consumes and cut the need for
For the second normal form stage to be reached, there are only two requirements that will need to be satisfied. One of these is that the database must already be in the first normal form. The other requirement is that the database must not include any partial dependencies. All of the attributes have to be dependent on the whole primary key. The Riordan Manufacturing database is in second normal form since there are no partial dependencies.
if A!B and B!C, then C is transitively dependent on A via B (provided that A is not functionally dependent on B or C) Third Normal Form (3NF) is a relation that is in first and second normal form in which no Non- Primary key attribute is transitively dependent on the primary key.
2NF is used to eliminate any partial dependencies and ensure that all non-key columns depend on the entire primary key.
This document is set up to give a planned view of an initial study of a new database design to be incorporated by a client’s day-to-day operations. The study done also will shed some light on the company’s operations, structure, database constraints and objectives.