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Relational data base system is the most important data base systems used in the software industry today. One of the most understandings data base systems is MS SQL Server.
Relational databases are using common fields, which attribute are that appear in more than one table to establish relation between the table and form an overall data structure. These types of design called as relational databases.
Data base models
In SQL Server many of data models are used in earlier times and one by one it modified as user requirements. Data model is theoretical part of the database and it determines what types of data can store in data base. There are many of data models are having this industry.
Objectional database model
There are lots of techniques used on database model. Most databases are made by using one particular data mode. Any of logical models can modify as similar to physical implementation since every modification logical or physical are effect on performance
This model is very simple data model. Its like plan text or mixed text which contain one record per line. The flat model is consist 2D array format. In this model all data in given column are assumed to be similar and all data in row have to relate each other. This model can only add same types of records to database.
D:\to write\icbt project\assignments\DAD\pic\280px-Flat_File_Model.svg.png
Figure flat model
Advantages in flat model
Record can read and write faster than relational database.
Disadvantages in flat model
Flat database wasting memory on computer to store data.
The hierarchical model is organized there data using tree structure. That structure allows to repeating information using parent child relationship. And this relationship known as one to many relationships.
Figure hierarchical model
Advantages of hierarchical modelâ€™
This database easy to maintain.( ex: if you delete folder in the database you would delete all the folders and files it contain)
Disadvantage of hierarchical model
Data can repeated
Data access time too long
The network model organized data by using two fundamental constructions those are records and sets. The records contain fields in the table and sets define relationship between records. Records are owner of any number of sets and member in any number of sets.
Figure network model
Advantages of network model
Network model is easy to design
Can handle more relationship types
Can access to data very easily and speed
Disadvantages of network model
Database management system is not user friendly
Network model may have many deferent records containing unique identify and it shows many too many relationship also. It contains owner record and member record.
1 owner ------ many members
Many owner --------- 1 member
Figure relational model
Advantages of relational model
User can create relationship database
Inside the tables there are using primary
Primary keys making relationship between alternative keys in other tables
Disadvantages of relational database model
The data can be delete if keys over lap in requested made by creator
Database management system
Database management system is a computer program that control maintenance. Creations and use database. It allows handling database to users. And this allows to integrated collection of data on the database. It allows different application programs to access easily to the same database.
Entity relation diagram of order system
Figure ER diagram
Relation schemas of order system
Customer with order
Figure customer with order schema
Customer ( Cus_ID, name, NIC, Contact_No, Address)
Order (Order_ID, Product_ID, Cus_ID, Quantity, Price)
Product with supplier
Figure product with supplier schema
Product ( Product_ID, name, Quantity, Price, Sup_ID)
Supplier (Sup_ID, Name, Contact_No. Address, NIC)
Product with order
Figure product with order schema
Product (Name, Produt_ID, Quantity, Price)
Order (order_ID, Product _ID, Cus_ID, Quantity, Price)
Normalization is typically a refinement process after the initial exercise of identifying the data objects that should be in the database, identifying their relationships, and defining the tables required and the columns within each table.
In relational database design, the process of organizing data to minimize redundancy. Normalization usually involves dividing a database into two or more tables and defining relationships between the tables. The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database via the defined relationships.
There are three main normal forms, each with increasing levels of normalization:
First normal form (1NF) sets the very basic rules for an organized database:
Eliminate duplicative columns from the same table.
Create separate tables for each group of related data and identify each row with a unique column or set of columns (the primary key).
Second normal form (2NF) further addresses the concept of removing duplicative data:
Meet all the requirements of the first normal form.
Remove subsets of data that apply to multiple rows of a table and place them in separate tables.
Create relationships between these new tables and their predecessors through the use of foreign keys.
Third normal form (3NF) goes one large step further:
Meet all the requirements of the second normal form.
Remove columns that are not dependent upon the primary key.
Relational database systems are the most important database system used in the software industry today. One of the most outstanding systems is MS SQL Server there are a couple of reasons why SQL Server is the best choice for a broad spectrum of end user and database programmers building business applications. SQL Server is certainly the best database system for windows operating systems because it is tightly integrated with them. The number of installed windows systems increasing rapidly. And due to the best integration SQL Server is certainly a big database system.
Second SQL Server is the easiest database system to use in additional to the well-known user inter face Microsoft offers several different tools too help create database objects, tune database applications and manage system administration tasks.
Third building at least four products in one relational database engine analysis services, reporting services and integration services also brings the overall system to the winning position. A possibility to use one system for operational tasks as well as for business intelligence is what user want and need.