It sounds impossible but we all know that
this is now one of the main requirements for any business or institution to run
effectively – Information Systems or Information technology .
Because time it is now a very important
resource, we must create more and more innovative and effective computerised
systems that can help us reduce time spending for doing different tasks while
we are in control of the workload, and earn money in the same time.
A library is a complex system based on
multiple entities that are interrelated, all orbiting around one single element
– information.
Should we have a good understanding and to
be able to develop an effective LMS, we need to identify the entities and their
specific data so that we can establish their relations and how they influence
one another.
Slide
2
But before diving into library entities
and analyse each of them, I wish to stop and have a look to Data Modelling.
Data
Modelling helps us to basically give a shape to all
data and information we know.
It
is, if you like, as when we were kids and we used to play with coloured
modelling clay. We have had a piece of that clay with no sense, and we used to
transform it into a dinosaur or a frog. J
Something that our minds as kids could see a sense into.
Obviously, my example is a very primal one.
But through analogy, we can see data modelling as transforming chaotic data or
large amounts of data into systems that our mind can understand better and work
better with.
A definition of data modelling is that data
modelling is the process of sorting and storing data, organising the entities and
their data in such way to show how they interrelate to each other in order for
the management and IT professionals to understand and apply this model for
organising better work flows and subsequently, better communication, in the
library, in our case.
Slide
3
Why is data modelling technique a useful
tool?
It may look complicated at one first view.
But as in a library we need to arrange all the books on shelves and we need to
make sure we can have easy access to each of them, is the same thing with data
modelling techniques.
We will have a look at few data modelling
techniques.
A data modelling technique as mentioned
earlier, helps us to access very quick a large amount of data organised into
categories. In a college library, there are a number of entities as: management, staff, students, borrowers and
last but not least the books. All these
entities are interrelated one to another and a poor management of data can
cause massive disruption within the work flows.
We need to be able to visualise the
relationships between these entities. Having a list with these entities and
their related data as well as being able to visualise the relationships between
them, help us design efficient, business focused databases.
Essentially, a logical Entities
Relationships Diagram will enable us to effectively see the relationship
between existent entities or glossary terms. (Brandenburg, 2019)
Slide 4 – We are now going to have a look at few data
modelling techniques punctually.
Data Dictionary
Glossary
Entity Relationship Diagram or ERD
Data dictionary
The Data Dictionary model provides information
about each attribute. We first need to identify the attributes and specific
data about them. We can then organised them into a data dictionary.
Whenever we have
created spreadsheets with records of our contacts for example, that is actually
creating a data dictionary.
A data dictionary
has three main element
Attribute
Attribute type
Optional/required
Attribute is a unique identifier, expressed
in the typical language of the business that the data dictionary is created
for, in our example: data about the student, as name, email address, phone
number, address, city, etc.
Attribute type defines what type of data is
allowed in that field. Most common types include text, numeric, mixed, date or
time etc. In our example, you can see that the phone number attribute is
numeric, but the email is mixed which means an email address can be typed as
letters, symbols, and numbers. Also, the name attribute is Alpha which means
the name can be typed using alphabet, etc.
Optional/required indicates if other
information is required in an attribute before saving it. In our example, the
rules of inserting data before being saved are optional, but this particular mapping
requires it. For example, length and rules are required information for each
data. In the rules column is specified that the name should be typed in as at
least 2 words – name and surname right? Also, the email address must contain
the symbol for “at” , and for the phone number will not be accepted all 555
numbers. (Brandenburg,
2019)
“As you can see, a data dictionary defines critical
information about each attribute in a business-focused way. It also
organizes information that might otherwise be scattered across multiple
different documents and specs, making it easier for your database developer to
design or update a database that meets business requirements.” (Brandenburg, 2019)
Slide 5
Another data modelling technique is Glossary.
A glossary is
used to ensure that all stakeholders (business and technical) understand what
is meant by the terminology, acronyms, and phrases used inside an organization (Brandenburg,
2019).
A glossary helps
stakeholders whether they are business or technical to understand all
terminology used in that specific business environment. They can communicate
better and quicker using same terminology.
Glossary is a list
of terms and their definitions. In other words, everyone who can have access at
the glossary can understand better of what certain terms refers for so
essentially they can better understand its requirements. Improves communication
and it is a reference tool and a modelling technique for capturing terms,
definitions, and variations as they come up within the business process.
Imagine a meeting
of stakeholders, and everyone using their own words for specific elements or
important decision takers do not understand the meaning of a specific word in
that particular business context. J
A glossary helps
to clarify unfamiliar or new terms and is very important for the business,
before taking any step further.
Slide
6
And
last but not least Entity Relationships Diagram
ERD it is a data modelling technique that
describes how entities or concepts or things relate to each other. From a
logical point of view ERD shows how the terms in the glossary relate to one
another.
“They are
especially helpful in clarifying information models for relational databases
and helping business users understand database structures at a high level and without
details.” (Brandenburg, 2019)
This tool helps
communicating how the information is stored and what is the business
perspective about relationships.
A business concept
could be for example, borrowing books from a library. Through a short analysis
we can identify that a student can borrow one or more books from the library.
But a book cannot be borrowed by multiple students.
But the book
itself it is written by an author and published by a certain publisher and it
might be just a limited number of that specific book so, even though the same
book can be borrowed by 2-3 students, it will still be a limited numbers of
borrowers that can book that book.
Also, a student
can borrow for multiple times books from library, but what happens if the
student do not return those books? As we all know, they can pay a fine. But if
the fine is not paid, then eventually, the student will not be allowed to
borrow from that library, until he pays the fine.
So first are the
entities: students, books, workers, and librarian
Second are the
relationships between them: a student it is able to borrow 2 books only, but a
book cannot have 2 borrowers, so we are looking at this relationship as one to
many. But could be when same book can be borrowed by 2 or more students because
there are more than one in the library. So now we are looking to many to many
type of relationship.
Third is
attributes. Attributes are the details within each entity. The student has a
name and student ID, the date when he registered with the library, how many
books he borrowed, etc. Books have an ISBN, they are on a certain subject and
written by a certain author or a group of authors.
Understanding this
relationships between these entities and having their attributes can help
creating a diagram which enables understanding of the processes that take place
within a library system and for a better management.
This ERD from the
slide, looks very complicated. The purpose of showing you this, is to
understand that this diagram as it is at the moment, can make the management
process very difficult.
Slide 7
In this slide we
will speak about identifying the entities and the specific data related to
them.
We have had a look
earlier to Glossary. If there is an existent glossary for the library we can
just take out from the glossary the entities.
But what happens
when we do not have a glossary?
We just pull the
nouns out from the process documents or from any required document
In our
presentation here, we managed to extract the entities for creating an ERD for
City College Library. Also we have added their attributes.
From the case
study, the entities that we extracted are:
Students is an
entity that has as attributes: student id, student college id, name, mobile,
student email, student username, student password, student address.
It is quite
straight forwards to observe that attributes are specific data related to the
entity.
Next entity in our
entity relationship diagram is books. Books attributes are: book id which can
be identified as ISBN, for example. ISBN stands for International Standard Book
Number. It is used internationally. This is a unique identifier for books.
Book student id,
book name, book author, book publication date, book type, book price, book
description are all attributes of book as entity.
Librarian entity
has its own attributes as well: librarian id, librarian name, librarian mobile,
librarian email, librarian username, librarian password, and librarian address,
but we considered as per case study is not essential in this situation.
Another entity is
book issues and as attributes has issue date, return date, fine for not return
The last entity
extracted it is reservations with reservation book id, reservation date,
reservation student id as attributes.
Slide 8
Entity
relationships diagram shows the relationships between these entities. We need
to understand how they are related to each other, so that we can create this
diagram.
And how we do
this?
We establish
through simple logic the relationships between present entities. These relationships
are also named cardinalities and they are represented through specific signs
that you can observe in our diagram.
For example, if we
take student and books, we can establish cardinality through asking 2
questions:
- How many students can have a book issue and how
many issues can have a student?
It may sound
strange at the beginning, but if we think logically, in our library environment, a student can have only
one issue, just to avoid fine accumulation in case the student do not return
the books in allocated time. However, when the student do not return the books,
the fine is unblocked and student must pay that fine. This is what triggers
another cardinality: one issue can have zero to one fine, but one fine can have
only one issue.
If we look at the
entity books and the entity issues, in City College Library, one book can have
only one issue. And we consider this as we established that each individual
book even it is a duplicate it has one individual ID. So, if one book can have
only one issue, then the same book as let’s say it is not available for
borrowing, can have zero to many reservations. But how many books can a
reservation have?
We decided that one
reservation can have many books. It is logical right? If one of our students
cannot borrow two or three books from the library as they are not available, he
can place only one reservation for all the books that he wants to borrow.
Slide 9
As we can see, ERD
it is a graphic illustration of how entities from an information system related
to each other.
In other words it
is a map showing how information flows within systems, in our case in a library
management system.
From a business
point of view, the library management can make better business decisions having
a clear understanding of the informational flow within the library.
Having used a
modelling technique for data base helps IT people to implement a software easy
to understand and to use for students and library employees.
Reduces the loss
of information and finances, as we have clearly identified each entity’s
attributes so we can control and avoid confusion, and operations disruptions.
Protects the
library most important assets – books, especially those that are difficult to
replace.
Establishes the
correct number of employees. For example, can reduce the number of employees
required to work, as the processes are centralised within an automatic
operating system for the library.
In other words,
with few clicks, one employee can create issues, check books availability, find
books, and prevent loss by automatically stopping students that did not return
books to borrow more.
Creates the possibility for the students to
check books availability and make reservations.
Eliminates
unnecessary processes within the library
Slide 10
An ERD can be seen
as a stage within a development process.
Having used this
data modelling technique, the library management can now have a clear
understanding of their assets, data base and data requirements, how entities
relate to each other and how an efficient information flow looks like.
Library has now
become a fast peace environment and without a good system in place that can
control operations, the management and employees – good old librarian, will not
be able to meet current requirements of being efficient.
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