Relational Database Management System [RDBMS]
Create a Database- Personal and business database need to be created and RDBMS programs will
help facilitate this process.
Database is made easier and faster because of these programs.
Many if them have templates to choose from so you do not have to start from
scratch, however, if needed you can also start on your own.
Information storage- Once your database is created, it is now easy to add information into your
Information retrieval- Since your database is created in a structured fashion, it is easy to
retrieve data. In databases, the means to retrieve data is by query.
Query is a request for specific information from the created database.
Information management- Allows you to utilize and modify the information in a database
according to your needs.
Information analysis- The most important function of the database is using it. Data
accumulated and gathered is an asset in this Information Age.
Print and Share information- For purposes of a "hard copy" information may be printed and
stored as back up copy in case the digital copy of the database
gets corrupted or damaged. Printed information is also necessary
for people who are not used to viewing data in the computer
monitor and prefers them on paper.
Qualities of Good Database Information
Information generated from a database is an asset, since it provides the user the necessary information for an informed decision. A businessman needs information to decide which diretion to take in his business endeavor by looking at sales, expenses, competition and products. In shcool, the teacher uses information generated from a database to determine the grades of students. Banks need to process big volume of data to approve loan appications, process customer deposits and withdrawal and foreign exchange transactions. ETCETERA!
1.) Accurate information- it needs to be error free to have good database information, having inaccurate reports could mean disastrous results for others who are using that information.
2.) Organized information- means that the reports maybe arranged to suit the needs of the decision maker.
3.) Timely information- means that the report should be useful at the moment it is generated.
4.) Verifiable information- means that the report can be proven to be correct or incorrect.
5.) Accessible information- means that the database report is available to the person who needs it at anytime.
6.) Economical information- means information generated from a database program should be cost-effective to produce.
7.) Useful information- means the report should have meaning to the people who get them.
Relational Database Terminologies
Data- It is a number or value found and stored in the database.
Information- It is a data that has been processed thereby making it relevant and meaningful
to the person viewing it.
Null- It is used to represent value that is unknown or missing.
Table- It is the main structure in the database.
Field- It is the smallest structure of a data from a larger database structure in a relational
View- It is also known as the virtual table.
Keys-These are the fields that serve specific purposes within a table.
Relationships- They exist when two or more tables have connection or association.
Relationships in relational database exist when two or more tables are connected by the following conditions:
* Primary Key
* Foreign Key
* Linking table is a table that establishes a connection bet. two or more tables.
Relationships are important because they ensure data integrity since they eliminate redundant data. Relationships also help as means to define views.
Types of Relationships
When two or more tables are related, there exist bet. them a specific type of relationship and there are three types of possible relationships.
1.) One-to-One relationships
This relationship exists between tables when only one record of the first table is related to only one record to a second table, and only one record of the second table is related to only one record to the first table.
2.) One-to-Many relationships
This relationship exists bet. tables when one record of the first table can be related to one or more records to a second table but only one record from the second table can be related to a single record in the first table.
3.) Many-to-Many relationships
This relationship exists bet. tables when one record of the first table can be related to one or more records to a second table and one record from the second table can be related to one or more records to the first table.
Designing a Database
1.) Define the purpose of your database.
2.) Determine the tables that you need in the database.
3.) Determine the fields that you need in the database.
4.) Identify the unique field values that will allow Access to connect information in a separate table.
5.) Determine the relationships bet. tables.
6.) Test the design by entering sample data
3 Phases of Database Design
Data Definition (1)
-wherein all the data and information for database are collected and determined.
Data Refinement (2-4)
-wherein the data collected are refined by adding or removing unnecessary data.
Establishing Relationship (5-6)
-wherein links between the information are established.
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