Udjuni.com

Mathematics

Science

Computing

Accounting

Business

History

Agriculture

Biology

Database Design

After gathering and analyzing your requirements, and depending on whether or not your application needs a database to store information; database design is the next big thing. This comes even before you start coding the application program. The reason for this is that, the application program is mainly going to serve as a tool to insert, manipulate, analyze and present information to the end user. Thus until you have good database design, your application could be useless. It may have to deal with a lot of duplicates and anomalies that would slow down or consume a lot of your computing resources; which in the process could frustrate users and give them a reason to reject the use of your application.

What does the database design phase entail?

To start with, every database designer has to identify entities that are important to their business process. Once entities are identified, the database designer goes through a process called Database Normalization.

Database Normalization is a process during which identified entities or tables are tested for certain dependencies among their attributes and other entities.

Normal forms:

In theory there are at least five different normal forms. Usually the designer checks for the first three normal forms, any database that passes the third normal form is considered adequately normalized.

First Normal form:

- A table that is in first normal form must only have one column representing one value. For example a column named book title should only hold the title value and nothing else.
In other words every column must be atomic or single valued .

If for any reason, you encounter a column with multiple values, such values should be separated into two columns or attributes.

In short, to satisfy the first normal form rule, you eliminate repeating information by creating separate tables for related data.

Second Normal form:

- A table is in second normal form when it is in the first normal form and there is no nonkey column that is dependent on a partial key of that table. This means if fields in your table are not entirely related to your primary key then those fields will have to be moved to separate table.

Third Normal form:

- when the table is in second normal form and there are no functional dependencies among nonkey columns. In other words, no column should depend on other nonkey column. If such fields do exist then move them to a separate and related table.

To summarize this posting, here are steps you would follow if you are to develop a usable database-driven application. It is often cited that the biggest problem with most applications is the lack of forethought on the part of their developers. Before you start coding, take a little time to think about what data your application is going to hold, the scalability of your system and the relationships among data entities.

ln general, design process include the following steps:

clear definition of your objectives. What is it that you want from this application?
once you know what you want, use that information to design your data structures, in this case your tables and attributes or fields.
Clearly establish relationships among your entities.
Define and implement business rules
Then you can create the application to handle the logic and presentation to the application users.

Creating database tables with SQL
To create a table in SQL, you use a command that requires the name of the table as well as names and data types of the fields of that table. In general, the syntax for creating a table is as follows: CREATE table_name ( column_name data_type); The table nam

Creating and dropping SQL Views
In SQL, a view is like a virtual table. It be haves like a table except it does not store any data. Meaningful use of a view is usually to gather and simplify presentation of data from multiple tables. A view is compiled once and is stored on the database server and can be used wh

Creating your business web site
There are thousands of business websites on the World Wide Web. These websites serves as a means to inform your customers, suppliers, media contacts and other interested parties about your business and its offerings. Thus it is important to deliver essential information in a wa

Database schemas, domains and constraints
There is more to a database than just a collection of tables. In addition to tables, there are structural aspects that maintain the integrity of data stored in databases. This tutorial will cover the structural aspect of any relational database. These include schemas, domains and constraints.

Legal Business Forms
Now you are ready to start a business, you have fully or partially secured your starting capital. You have also done your market research and concluded that your business idea is viable. Now what? Now you have to register your business. There are several advantages to registering your business as le

Dealing with HTML forms
HTML forms are used to acquire and work with user input. As you may have noticed in the scripts we have used so far, every variable that was meant to hold user input had been given a value within that script. To get the actua

Selecting data from multiple tables
So far we have covered methods of retrieving data from single table. In real life however, you hardly get to only retrieve data from one table. In other words, to retrieve and interpret information, you normally get such information from different tables each of which will contain only information a

Forms Of Ownership

forms

Understanding Databases
In any relational database system, data is stored in what is called a table. Each table is made up of rows and columns. The idea with creating tables is based on the notion that each table should contain data about one and only