Wednesday, 16 September 2015


Database – Maintains info about various types of objects ,events,people and places.

Database models include :

Hierarchical Database Model 

Network Database Model

Relation Database Model

Entities and Attributes

Entities -  a person , place , thing or event about which info is stored.

Attributes – characteristics or properties of an entity class.

Keys and Relationsips

Primary key -  a field that uniquely identifies a given entity in atable.

Foreign Key – a primary key of one table that appears an attribute in another table and acts.

Relation Database Advantage
-       -   Increase flexibility
-        -  Increased scalability and performance
-       - Reduces info redundancy
Database Mangement System

Data Driven Web Sites
        An interactive web site kept constantly updated and relevant to the needs of customer.

Advantage :

1. Development
-    allows the owner to make changes at any time.
2. Content Management
-    Requires a programmer to make updates.
3. Future Expandability
-   Enables the site to grow faster than would be possible with a static site.
4. More Efficient
-   Computers are excellent at keeping volumes of information intact.

Intergrating Information among Multiple Databases

Intergration – allows separate systems to communicate directly with each other.

1. Forward Intergration
-   takes info entered into a given system and sends it auto to all downstream system and processes.

2. Backward Intergration
-   takes info entered into agiven system and sends it auto to all upstream systems and processes.


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