1.Menu-Based Interfaces for Web Clients or Browsing :
These interfaces present the user with lists of options, called menus, that lead the user through the formulation of a request. Menus do the specific commands and syntax of a query language; rather, the query is composed step by step by picking options from a menu that is displayed by the system.
Pull-down menus
are popular used in Web-based user interfaces.
They are also often used in browsing interfaces, which allow a user to look through the contents of a database
in an exploratory and unstructured manner.
2. Forms-Based Interfaces :
A forms-based interface displays a form to each user. Users
can fill out all of the form entries to insert new data, or they fill out only
certain entries, in which the DBMS will retrieve
matching data for the remaining
entries.
Forms
are usually designed and programmed for naive users as interfaces to transactions.Some systems
have utilities that define a form by letting the end user interactively construct a sample form on the screen.
A)Graphical User Interfaces :
A graphical User interface (GUI) typically displays
a schema to the user in diagrammatic form. The user can then specify a query by manipulating the diagram.
In many cases, GUIs utilize both menus and forms. Most GUIs use a pointing device, such as a mouse, to pick
certain parts of the displayed schema diagram.
B) Interfaces for the DBA :
Most database systems
contain privileged commands that can be used only by the DBA's staff. These include commands
for creating accounts,
setting system parameters, granting account authorization, changing a schema,
and reorganizing the storage structures
of a database.
Database Models:
A Database
model defines the logical design
and structure of a database
and defines how data will be stored,
accessed and updated
in a database management system.
While the Relational Model is the most widely used database
model, there are other models too:
· Hierarchical Model
· Network Model
· Entity-relationship Model
· Relational Model
· Hierarchical Model
· Network Model
· Entity-relationship Model
· Relational Model
Hierarchical Models:
This
database model organises data into a tree-like-structure, with a single root, to which
all the other
data is linked.
The heirarchy starts
from the Root data,
and expands like a tree, adding child nodes to the parent nodesstem.
In this model, a
child node will only have a single parent node. This model efficiently describes many real-world
relationships like index of a book, recipes etc.
In hierarchical model, data is organised into tree-like structure with one one- to-many
relationship between two different types of data, for example,
one department can have many courses, many professors and of-course many students.
Network Model:
This
is an extension of the Hierarchical model. In this model data is organised
more like a graph,
and are allowed
to have more than one
parent node.
In this database model data is more related
as more relationships are established in this database
model. Also, as the data is more related, hence accessing
the data is also easier and fast. This database model was used to map many-to-many data relationships.
This was the most
widely used database model, before Relational Model was introduced.
Entity-relationship Model:
In this database model, relationships are created by dividing object of interest
into entity and its characteristics into attributes.
Different entities
are related using relationships. E-R Models are defined to represent
the relationships into pictorial form to make it easier for different
stakeholders to understand.
This model is good to design a database,
which can then
be turned into tables in relational model(explained below).
Let's take an example,
If we have
to design a
School Database, then Student
will be an entity
with attributes name, age,
address etc. As Address
is generally complex, it can be another entity with attributes street name, pincode, city etc, and there will be a relationship between them.
Relational Model:
In this model, data is organised in two-dimensional tables and the relationship is maintained by storing a common field.
This model was introduced by E.F Codd in 1970, and since
then it has been
the most widely used database model, infact, we can say the only database model used around the world.
The basic structure of data in the relational model is tables.
All
the information related to a particular type is stored
in rows of that table,hence tables are also known as relations in relational model.
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