Operational data are consolidated and control centrally.
It minimized data redundancy. Inconsistency can be avoided. suppose in the file of HOD, a secretary's name is peace John and in office of registrar, the same secretary's name may be written in the file as Peace john n. Thus it is clear that if a given name is prepared in a single entry inconsistency can be avoided
data can be shared
standards can be enforced by the DBA
Security can be enforced as DBA can define the access paths for accessing the data stored in database.
Data integrity can be maintained.
APPLICATION AREAS OF DATABASE: Database packages are used for information management. Any organization (industry or commercial) requires information to effectively run its day-to-day activities. Some of the organization that requires database are: Hotel, Population Management, Hospital, Bank, Prison, Supermarket etc.
FEATURES OF DATABASE
The data dictionary: The data dictionary is the heart of the database it can called up at any time to provide a description of the data. E.g. how many characters it has, the decimal point location, and so forth.
The query Mechanism: The query mechanism provides a way for database it can called up at any time to provide a description of the data. e.g. many students are there in very school? you may wish to verify and extract information like:
How many female students are there in your Hotel?
who were the students that fail to pay their school fees
Multiple Language reading capabilities: A good DBMS will be compatible with popular higher language such as Basic, COBOL and FORTRAI
Flexibility: A good Database will have a certain amount of flexibility relative to future changes. For examples, a well structured DBMS will allow fields of database files to be adjusted without a complete program rewrite.
Error Handling: a good DBMS will be able to save data in the event of a system failure instead of wiping it out when the power goes off or when some other system interrupt occurs. This is contrary to word perfect programmes.
Documentation and Support: A reliable Database will have an explanatory of how it is structured and works. The documentation teaches new users the step by step operations to fully understand the system.
Hierarchical Database Structure: The hierarchical data structure presents data to users in a tree-like structure. Here within each record, data elements (fields) are organized into pieces of records called segments.
To the user each record looks like an organization chart with one top record called the root. An upper segment is connected logically to a lower segment in a parent-child, but a child can have only one parents.
DATABASE FILE
In generic data base, data is logically organized into
File- is a group of related fields
Record- is a group of related fields
Fields - is also called data elements it is made up to two or more related characters.
Character - is the smallest unit of information
Data types include
Text
Number
Logical (Yes or NO) Memo
Currency
Date/Time
Decimal
A Database is Ms Access
About Designing a Database
Good database design ensures that your database is easy to maintain. You store data in tables and each table contains data about only one subject. Such as Diploma 1 Business. Therefore you update a particular piece of data, such as RegNo. in just one place and that change automatically appears throughout the database.
A well designed database usually contains different types of queries that show the information you need. A query might show a subject of data, such as all female students.
Before you use Microsoft Access to actually build tables. queries forms, and other objects it's a good idea to sketch out and rework your design on paper first. You can also examine well designed databases similar to the one you are designing, follow these basic steps when designing your database.
DETERMINE THE PURPOSE OF YOUR DATABASE
The step in designing a database is to determine its purpose and how it's to be used: Talk to people who will use the database.
DETERMINE THE FIELD YOU NEED IN THE DATABASE
each field is a fact about a particular subject. For examples, you might need to store the following facts about Diploma business: Name, RegNo, Sex, Class, LGA. State and Phone number. You need to create a separate field for each of this.
DETERMINE THE TABLES YOU NEED IN THE DATABASE
Each table should contain information about one subject. Your list of fields will provide clues to the tables you need. For example, if you have a HireDate Field, its subject is an employee, so it belongs in the Employees table. You might have a table for customers. A table for products, and a table for Orders.
DETERMINE WHICH TABLE EACH FIELD BELONGS TO
when you decide which table each field belongs to keep these design principles in mind.
Add the field to only one table. Don't add the field to a table if it will result in the same information appearing in multiple records in that table. if you determine that a field in a table will contain a lot of duplicate information, that field is probably in the wrong table
IDENTIFIED THE FIELD OF FIELD WITH UNIQUE VALUES IN EACH RECORD
in order for Microsoft Access to connect information stored in separate tables for example, to connect a customer with all the customer's orders each table in your database must include a field or set of fields that uniquely identifies each individual record in the table. Such a field or set of fields is called primary key.
DETERMINE THE RELATIONSHIPS BETWEEN TABLES
Now that you've divided your information into tables and identified Primary Key fields, you need a way to tell Microsoft Access how to bring related information back together again in meaningful ways. To do this, you define relationships between tables. You may find it useful to view the relationships in an existing well designed database such as the Northwind sample database.
To begin database project in Ms Access