...Normalize? 3- Normalization & Its types. 4- Applications of Normalization. 5- Conclusion Introduction While working with databases, one must have got chances to hear the term normalization. If someone asks "Is that database normalized?" or "Is that in BCNF?" All too often, the reply is "Uh, yeah." Normalization is often brushed aside as a luxury that only academics have time for. However, knowing the principles of normalization and applying them to daily database design tasks really isn't all that complicated and it could drastically improve the performance of DBMS. In this report, I'll introduce the concept of normalization and take brief look at the most common normal forms. Why to normalize? While designing a database, the main problem existing in that “raw” database is redundancy. Redundancy is storing the same data item in more one place. A redundancy creates several problems like the following: 1. Extra storage space 2. Entering same data more than once. 3. Deleting data from more than one place. 4. Modifying data in more than one place. 5. Anomalies may occur in the database if insertion, deletion, modification etc are not done properly. It creates inconsistency and unreliability in the database. To solve these problems, the “raw” database needs to be normalized. Normalization Normalization is the process of efficiently organizing data in a database. There are two...
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...Running Head: DATABASE NORMALIZATION Database Normalization *************** IST 7000 October 2006 Table of Contents ABSTRACT 3 Brief overview 4-5 Types of Normal Forms 5-9 Advantages and Disadvantages 9-10 Normalization Best practices 10-11 Conclusion 11-12 References 13 Appendix A 14 Example Normal Form Diagrams 15 Abstract In relational databases, normalization is a process that is used to eliminate redundancy, reduce the potential for anomalies during data processing, and maintain data consistency and integrity through out the database. It is a design technique used primarily as a guide in designing relational databases. Normalization is essentially a two step process that puts data into tabular form by removing repeating groups and then removes duplicated data from the relational tables. The theory of normalization is based on the concept of normal forms introduced by Edgar F. Codd in 1970. I choosed this topic because this is one of the areas in my role as a database administrator where I’m weak. During my training as a database administrator, I was never really offered a database design class, however, while at work, I have been occasionally given the challenging task of reviewing a data model and giving...
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...Database Normalization and Logical Process Concept paper This short paper will explain with a simple example the process and the need of normalization in the most of the business databases. Complete proposal break down (Timeline phases, Financial phases) will be submitted per management request. Overview At first any database should be designed with the end user in mind. Logical database design, also referred to as the logical model, is the process of arranging data into logical, organized groups of objects that can easily be maintained. The logical design of a database should reduce data repetition or go so far as to completely eliminate it. The needs of the end user should be one of the top considerations when designing a database. We should remember trough all design process that the end user is the person who ultimately uses the database. There should be ease of use through the user's front-end tool (a client program that allows a user access to a database), but this, along with optimal performance, cannot be achieved if the user's needs are not taken into consideration. Some user-related research and design considerations in any business database include the following: What data should be stored in the database? How will the user access the database? What privileges does the user require? How should the data be grouped in the database? What data is the most commonly accessed? How is all data related in the database? What measures should be taken to ensure accurate data...
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...Normalization In normalized database, the database has more number of tables. As normalization means creating more tables from lesser ones. As the numbers of tables created are higher, the more joints will be needed to get at the data. Normalization normally removes the duplicity i.e. redundant data which results in increase in database performance. Impacts of Normalization on Database Performance Normalization has various impacts on database performance. These are: 1. Removal of Redundancy: Normalization increases performance by removing the redundancy. 2. Less Storage Space: Normalization results into less storage space, because the redundant data is removed. 3. Reliability: It helps in producing the reliable information. 4. Efficient System: In order to provide efficient system, Normalization plays a very important role. In spite of increasing performance, Normalization requires much access time to execute the queries. Moreover, it also needs more number of joints. Example: We have two tables i.e. orders and customers 1. Orders table: * Select * from orders; Order_id | Order_name | Customer_id | 1 | Order_1 | 1 | 2 | Order_2 | 8 | 4 | Order_4 | 2 | 5 | Order_5 | 3 | 7 | Order_7 | 3 | 9 | Order_9 | 1 | 10 | Order_10 | 3 | 2. Customers table: * Select * from customers; Customer_id | Customer_name | 1 | Customer1 | 3 | Customer3 | 5 | Customer5 | * select * from db.orders O INNER JOIN db.customers C ON O.Customer_ID=...
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...1.Introduction Relational database design theory is mainly based on a class of constraints called Functional Dependencies (FDs).FDs are a generalization of keys. This theory defines when a relation is in normal form (e.g., in Third Normal Form or 3NF) for a given set of FDs. It is usually a sign of bad DB design if a schema contains relations that violate the normal form requirements. If a normal form is violated, data is stored redundantly, and information about different concepts is intermixed. To reduce the redundancy in a given relation we need to decompose it in two or more sub relations . Decomposition into highest normal forms required maintaining properties like loss less join decomposition and dependency preserving decomposition. To normalize a relation R we have to remove certain dependencies that exist in it like partial dependency& transitive dependency. Basic definitions 1.1 Functional dependency: In a given table, an attribute Y is said to have a functional dependency on a set of attributes X (written X → Y) if and only if each X value is associated with precisely one Y value. For example, in an "Employee" table that includes the attributes "Employee ID" and "Employee Date of Birth", the functional dependency {Employee ID} → {Employee Date of Birth} would hold. It follows from the previous two sentences that each {Employee ID} is associated with precisely one {Employee Date of Birth}. 1.2 Trivial functional dependency A trivial functional dependency...
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...Why Normalization Failed to Become the Ultimate Guide for Database Designers? Marin Fotache Alexandru Ioan Cuza University of Iasi, Romania Faculty of Economics and Business Administration Dept. of Business Information Systems Blvd. Carol I, nr. 22, Iasi, 700505, Romania Tel: + 40 744 497 654, Fax: + 40 232 217 000 fotache@uaic.ro ABSTRACT With an impressive theoretical foundation, normalization was supposed to bring rigor and relevance into such a slippery domain as database design is. Almost every database textbook treats normalization in a certain extent, usually suggesting that the topic is so clear and consolidated that it does not deserve deeper discussions. But the reality is completely different. After more than three decades, normalization not only has lost much of its interest in the research papers, but also is still looking for practitioners to apply it effectively. Despite the vast amount of database literature, comprehensive books illustrating the application of normalization to effective real-world applications are still waited. This paper reflects the point of 1 view of an Information Systems academic who incidentally has been for almost twenty years a practitioner in developing database applications. It outlines the main weaknesses of normalization and offers some explanations about the failure of a generous framework in becoming the so much needed universal guide for database designers. Practitioners might be interested in finding out (or confirming)...
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...the arrow 4.7 keys is a group of one or more attributes that are uniquely identifies a row 4.8 yes and yes 4.9 Deletion anomaly is a removal of a row of data but it also removes every relationship with that row. Ex: a removal of a computer in an inventory with everything to do with that computer 4.10 Insertion anomaly is adding an entry in a database but can because it hast. Ex: adding a computer to a computer inventory but cant 4.11 4.12 second normal form is the second step in normalization in a database. 4.13 third normalization form is the 3rd step in normalizing a database 4.14 BCNF is a form of database normalization 4.15 multi-value dependency occurs when the presence of one or more rows in a table implies the presence of one or more other rows in the same tables. Ex: Car Company that manufacture many models of cars, but always make both red and blue colors of each models. 4.16 4.17 Forth-normal form is a level of database normalization where there is no non-trivial decency other than a candidate key 4.18 Domain/key normal form is a normal form used in a database normalization that requires that the database contains no constraints other domain constraints and key constraints 4.19 4.22...
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...| National Park Service System | Normalization Summary | Thurmond Burdette 4-14-2015 | In this summary you will understand the importance of normalization for this project. Normalization is the process the team used to efficiently organize data within the database. The goal of this process is to remove repeated data such as storing the same data in more than one table, and ensuring data dependencies. The ultimate goals of the normalization process ensures that redundancy is reduced and that data is organized so that it is relatable, decreases database space allowing the data to be understood. The NPS (National Park Service) has contracted with our organization to track data of visitation to all 51 of their parks which have recently experienced an increase in visitation. The data will reflect how work load demand and distribution affect funding and salary increases going forward. Presently utilizing Microsoft Access the NPS has used this relational database to keep data up to date and would like our analysts to create a “back-end” process for the system currently being used. The Normalization Process streamlines the above process by using guidelines that begins with the lowest form up to the fifth normal form. The first and second normal form sets a framework for the data to be organized and addresses duplication of data. The data tables in these two steps are organized independently and clearly identifiable. The Second normal form...
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...from "Databases R US" IT consulting and managing firm. You just got hired by "Home Solutions Inc" a construction and Parts Company to help them with their customer and parts data management. Unfortunately, the company has been depending on the owner's nephew for their data needs and Joe has done his best to come through for the family business. His lack of experience with data management is hurting the business as they have been unable to successfully keep track of their inventory system, customers and sales. Joe has put together a spreadsheet, see below, and they have been using it as a database of sorts, to track their customers and inventory. Your specific tasks to help the business are in parenthesis are the percentages that correspond to the per item payment (grade weight): 1) Review the existing spreadsheet, and their sample data and make any assumptions you need about the company. Make any comments about the approach that you are going to follow, as you see fit. (10%) 2) Redesign the spreadsheet into a database with tables, add any fields that you think could be useful, even though it is not absolutely necessary. Explain your actions as you go along. 3) Perform a functional dependency analysis, and include it as part of your deliverables, for every step of the normalization process (25%) 4) Clearly take the existing un - normalized structure through distinct 1NF, 2NF and finally 3NF stages, using the shorthand representation. All three stages of normalization have...
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...Chapter 5 Normalization of Database Tables Discussion Focus Why are some table structures considered to be bad and others good and how do you recognize the difference between good and bad structures? From an information management point of view, possibly the most vexing and destructive problems are created through uncontrolled data redundancies. Such redundancies produce update and delete anomalies that create data integrity problems. The loss of data integrity can destroy the usefulness of the data within the database. (If necessary, review Chapter 1, Section 1.4.4, “Data Redundancy”, to make sure that your students understand the terminology and that they appreciate the dangers of data redundancy.) Table structures are poor whenever they promote uncontrolled data redundancy. For example, the table structure shown in Figure IM5.1 is poor because it stores redundant data. In this example, the AC_MODEL, AC_RENT_CHG, and AC_SEATS attributes are redundant. (For example, note that the hourly rental charge of $58.50 is stored four times, once for each of the four Cessna C-172 Skyhawk aircraft – check records 1, 2, 4, and 9.) Figure IM5.1 A Poor Table Structure [pic] |[pic] The figures shown in this discussion show the contents of the IM_Discussion database. This database is located on the teacher’s CD. The | |Student Online Companion also includes SQL script files (Oracle and SQLServer) for all of the data sets used throughout the book. ...
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...Normalization of the ERD The Huffman Trucking Database (HTD) is normalizing up to 3NF level. The first step in normalizing is to fine the candidate key in the database. The “Employer ID Number”, “Driver Log ID”, and “Citation Number” are candidate keys in the database. First Normal Form (1NF) values of a database are: • Each column must have a unique name. • The order of the rows and columns doesn’t matter. • Each column must have a single data type. • No two rows can contain identical values. • Each column must contain a single value. • Columns cannot contain repeating groups. The tables in HTD consists unique names and each column has a single data type. Each table consists of primary key, which makes the row contain identical values. The HTD passes all the requirement of firs normal form. Second Normal Form (2NF) form with two conditions: • The table is in 1NF. • All the non key fields depend upon on all the key fields. All the three tables are depending upon the primary key or key fields; this makes the table to update anomalies. The HTD passes the requirement of second normal form Third Normal Form (3NF) form with two conditions: • The table is in 1NF. • It contains no transitive dependencies. A transitive dependency is when one non-key field’s value depends on another non-key field’s value. The drives log table need to driver log key to form 3NF, because Employee ID, Date, and Tractor ID are inter dependent. The other two table are depend upon the primary...
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...Functional Dependency is mainly known as Normalization. Professor Codd in 1970 was the first person to define it. There are three steps to this dependency. Normalization is used to eliminate the three types of anomalies which are insertion, deletion and update anomalies. The three normalization are what a database can suffer from. They also define what the database is about because of all the work that goes into it. The Insertion Anomaly is when some of the data cannot be added into the database. There are just certain areas of the database where information just cannot be added or else it would mess up the system or get you a big (OOOPS). Update an0omaly is when there is redundancy going on in the database which will cause changes to everything that is in the database. Instead of change one information and the database changing all of them, a person has to go and do it one step at a time. Deletion anomaly is deleting of some data that causes other information to be lost or deleted. Example -1. Assume the following relation Student-courses (Sid:pk, Sname, Phone, Courses-taken) Where attribute Sid is the primary key, Sname is student name, Phone is student's phone number and Courses-taken is a table contains course-id, course-description, credit hours and grade for each course taken by the student. More precise definition of table Course-taken is : Course-taken (Course-id:pk, Course-description, Credit-hours, Grade) According to the definition of first normal form relation...
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...Normalization of Database Tables l 4 4 4 Introduction to Normalization of Database Tables Normalization of Database Tables ISM 602 Dr. Hamid Nemati Introduction to Normalization of Database Tables 4 4 4 Objectives The idea of Dependencies of Attributes Normalization and Database Design Understand concepts of normalization (Higher-Level Normal Forms) Learn how to normalize tables Understand normalization and database design issues Denomalization Functional Dependency l Introduction to Normalization of Database Tables Examples of Functional Dependencies: l Introduction to Normalization of Database Tables l l A Functional Dependency Is A Relationship Between Or Among Attributes Such That The Values Of One Attribute Depend On, Or Are Determined By, The Values Of The Other Attribute(s). Partial Dependency: Is A Relationship Between Attributes Such That The Values Of One Attribute Is Dependent On, Or Determined By, The Values Of Another Attribute Which Is Part Of The Composite Key. Partial Dependencies Are Not Good Due To duplication Of Data And Update Anomalies; l l If we know an ISBN, then we know the Book Title and the author(s) l ISBN è Book Title l ISBN è Author(s) If we know the VIN, then we know who is the Auto owner l VIN è Auto_Owner If we know Student-ID (SID), then we can uniquely determine his/her Name l SID è S_Name Transitive Dependencies l Introduction to Normalization of Database Tables So Now what is Normalization...
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...Database Modeling and Design – 4th Edition (2006) Toby Teorey, Sam Lightstone, Tom Nadeau Exercises with Solutions – Solutions Manual ER and UML Conceptual Data Modeling Problem 2-1 Draw a detailed ER diagram for an car rental agency database (e.g. Hertz), keeping track of current rental location of each car, its current condition and history of repairs, and customer information for a local office, expected return date, return location, car status (ready, being-repaired, currently-rented, being-cleaned). Select attributes from your intuition about the situation, and list them separately from the diagram, but associated with a particular entity or relationship in the ER model. Solution to 2-1 Problem 2-2 Given the following assertions for a relational database that represents the current term enrollment at a large university, draw an ER diagram for this schema that takes into account all the assertions given. There are 2000 instructors, 4000 courses, and 30,000 students. Use as many ER constructs as you can to represent the true semantics of the problem. Assertions: An instructor may teach one or more courses in a given term (average is 2.0 courses). An instructor must direct the research of at least one student (average = 2.5 students). A course may have none, one, or two prerequisites (average = 1.5 prerequisites). A course may exist even if no students are currently enrolled. All courses are taught by exactly one instructor. The...
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...purpose of normalization is to create a stable set of relations is representative of the operations of an enterprise. By doing this we are able to reduce redundancy to save space and avoid inconsistencies in data. It also ensures that the design is free of certain updates, insertions, and deletion anomalies (Ricardo, 2012). With normalization as with most anything else there are advantages and disadvantages. The advantages of normalization are: ACID, which stands for atomicity, consistency, isolation, and durability. Atomicity means the transaction is a single unit. Either the entire set of actions is carried out or is not. Consistency means that the user ensures their transactions will leave the database in a consistent state. Isolation is the requirement that the final effect of the transaction appear as if it were executed one after another instead of concurrently. Durability is ensuring that the effects are permanently recorded in a database even if the system crashes before all its rights are made to the database (Ricardo, 2012). Another advantage of normalization is performance. Well-normalized databases are faster to write to and access. Disadvantages of normalization are: they are difficult and expensive to do, require great skill and experience to create correctly, require discipline to maintain, and requires skill and discipline to keep well indexed (Vera Huneeus, 2014). Utilizing someone who is experienced and skilled at normalization, a database can run...
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