Nnamdi Okoli
Logical Data Independence: This is the ability to change the conceptual schema without having to
change the external schemas and any application programs they are associated with.
Example: If I were to add an attribute Age_gender to the student table then the existing record being
utilized by the end-user of the department won’t get affected.
Physical Data Independence: While in the case of physical data independence, physical storage
structure or devices can be changed without affecting conceptual schema.
Example: Since it deals with the actual storage representation of the data, change physical media where
the student table is stored then it will not affect the existing table. Basically storing from a flash drive to
hard drive will not change content
Database architecture is the design, development, implementation and maintenance of computer
programs that store and organize information for use.
In 1-tier architecture, the database management system (DBMS) is the only entity where the user
directly sits on the DBMS and uses it. Like just accessing data stored on your hard drive.
In the 2-tier architecture, to access the data, the user must have an application through which the DBMS
can be accessed. The user will have a situation 2-tier architecture where they access the DBMS by
means of an application. The application is entirely independent of the database in terms of operation,
design, and programming.
3-tier architecture separates its tiers from each other based on the complexity of the users and how
they use the data present in the database. It will be the tier I will use because it gives the end users
access to information only relevant to them, tier one will require the end user to have the database and
tier 2 will give the end user too much information and ability to look at personal data of other users.