An ER diagram in DBMS (database management systems) is a lot like a storyboard for an animated TV show – it’s a collection of diagrams that show how everything fits together. Where a storyboard demonstrates the flow from one scene to the next, an ER diagram highlights the components of your databases and the relationships they share.


Understanding the ER model in DBMS is the first step to getting to grips with basic database software (like Microsoft Access) and more complex database-centric programming languages, such as SQL. This article explores ER diagrams in detail.


ER Model in DBMS


An ER diagram in DBMS is a tangible representation of the tables in a database, the relationships between each of those tables, and the attributes of each table. These diagrams feature three core components:


  • Entities – Represented by rectangles in the diagram, entities are objects or concepts used throughout your database.
  • Attributes – These are the properties that each entity possesses. ER diagrams use ellipses to represent attributes, with the attributes themselves tending to be the fields in a table. For example, an entity for students in a school’s internal database may have attributes for student names, birthdays, and unique identification numbers.
  • Relationships – No entity in an ER diagram is an island, as each is linked to at least one other. These relationships can take multiple forms, with said relationships dictating the flow of information through the database.

Mapping out your proposed database using the ER model is essential because it gives you a visual representation of how the database works before you start coding or creating. Think of it like the blueprint you’d use to build a house, with that blueprint telling you where you need to lay every brick and fit every door.


Entities in DBMS


An Entity in DBMS tends to represent a real-life thing (like the students mentioned previously) that you can identify with certain types of data. Each entity is distinguishable from the others in your database, meaning you won’t have multiple entities listing student details.


Entities come in two flavors:


  • Tangible Entities – These are physical things that exist in the real world, such as a person, vehicle, or building.
  • Intangible Entities – If you can see and feel an entity, it’s intangible. Bank accounts are good examples. We know they exist (and have data attributed to them) but we can’t physically touch them.

There are also different entity strengths to consider:


  • Strong Entities – A strong entity is represented using a rectangle and will have at least one key attribute attached to it that allows you to identify it uniquely. In the student example we’ve already shared, a student’s ID number could be a unique identifier, creating a key attribute that leads to the “Student” entity being strong.
  • Weak Entities – Weak entities have no unique identifiers, meaning you can’t use them alone. Represented using double-outlined rectangles, these entities rely on the existence of strong entities to exist themselves. Think of it like the relationship between parent and child. A child can’t exist without a parent, in the same way that a weak entity can’t exist without a strong entity.

Once you’ve established what your entities are, you’ll gather each specific type of entity into an entity set. This set is like a table that contains the data for each entity in a uniform manner. Returning to the student example, any entity that has a student ID number, name, and birthdate, may be placed into an overarching “Student” entity set. They’re basically containers for specific entity types.



Attributes in DBMS


Every entity you establish has attributes attached to it, as you’ve already seen with the student example used previously. These attributes offer details about various aspects of the entity and come in four types:


  • Simple Attributes – A simple attribute is any attribute that you can’t break down into further categories. A student ID number is a good example, as this isn’t something you can expand upon.
  • Composite Attributes – Composite attributes are those that may have other attributes attached to them. If “Name” is one of your attributes, its composites could be “First Name,” “Surname,” “Maiden Name,” and “Nickname.”
  • Derived Attributes – If you can derive an attribute from another attribute, it falls into this category. For instance, you can use a student’s date of birth to derive their age and grade level. These attributes have dotted ellipses surrounding them.
  • Multi-valued Attributes – Represented by dual-ellipses, these attributes cover anything that can have multiple values. Phone numbers are good examples, as people can have several cell phone or landline numbers.

Attributes are important when creating an ER model in DBMS because they show you what types of data you’ll use to populate your entities.


Relationships in DBMS


As your database becomes more complex, you’ll create several entities and entity sets, with each having relationships with others. You represent these relationships using lines, creating a network of entities with line-based descriptions telling you how information flows between them.


There are three types of relationships for an ER diagram in DBMS:


  • One-to-One Relationships – You’ll use this relationship when one entity can only have one of another entity. For example, if a school issues ID cards to its students, it’s likely that each student can only have one card. Thus, you have a one-to-one relationship between the student and ID card entities.
  • One-to-Many Relationships – This relationship type is for when one entity can have several of another entity, but the relationship doesn’t work in reverse. Bank accounts are a good example, as a customer can have several bank accounts, but each account is only accessible to one customer.
  • Many-to-Many Relationships – You use these relationships to denote when two entities can have several of each other. Returning to the student example, a student will have multiple classes, with each class containing several students, creating a many-to-many relationship.

These relationships are further broken down into “relationship sets,” which bring together all of the entities that participate in the same type of relationship. These sets have three varieties:


  • Unary – Only one entity participates in the relationship.
  • Binary – Two entities are in the relationship, such as the student and course example mentioned earlier.
  • n-ary – Multiple entities participate in the relationship, with “n” being the number of entities.

Your ER diagram in DBMS needs relationships to show how each entity set relates to (and interacts with) the others in your diagram.


ER Diagram Notations


You’ll use various forms of notation to denote the entities, attributes, relationships, and the cardinality of those relationships in your ER diagram.


Entity Notations


Entities are denoted using rectangles around a word or phrase, with a solid rectangle meaning a strong entity and a double-outlined rectangle denoting a weak entity.


Attribute Notations


Ellipses are the shapes of choice for attributes, with the following uses for each attribute type:


  • Simple and Composite Attribute – Solid line ellipses
  • Derived Attribute – Dotted line ellipses
  • Multi-Valued Attribute – Double-lined ellipses

Relationship Notations


Relationship notation uses diamonds, with a solid line diamond depicting a relationship between two attributes. You may also find double-lined diamonds, which signify the relationship between a weak entity and the strong entity that owns it.


Cardinality and Modality Notations


These lines show you the maximum times an instance in one entity set can relate to the instances of another set, making them crucial for denoting the relationships inside your database.


The endpoint of the line tells you everything you need to know about cardinality and ordinality. For example, a line that ends with three lines (two going diagonally) signifies a “many” cardinality, while a line that concludes with a small vertical line signifies a “one” cardinality. Modality comes into play if there’s a minimum number of instances for an entity type. For example, a person can have many phone numbers but must have at least one.


Steps to Create an ER Diagram in DBMS


With the various notations for an ER diagram in DBMS explained, you can follow these steps to draw your own diagram:


  • Identify Entities – Every tangible and intangible object that relates to your database is an entity that you need to identify and define.
  • Identify Attributes – Each entity has a set of attributes (students have names, ID numbers, birthdates, etc.) that you must define.
  • Identify Relationships – Ask yourself how each entity set fits together to identify the relationships that exist between them.
  • Assign Cardinality and Modality – If you have an instance from Entity A, how many instances does it relate to in Entity B? Is there a minimum to consider? Assign cardinalities and modalities to offer the answers.
  • Finalize Your Diagram – Take a final pass over the diagram to ensure all required entities are present, they have the appropriate attributes, and that all relationships are defined.

Examples of ER Diagrams in DBMS


Once you understand the basics of the ER model in DBMS, you’ll see how they can apply to multiple scenarios:


  • University Databases – A university database will have entities such as “Student,” “Teacher,” “Course,” and “Class.” Attributes depend on the entity, with the people-based entities having attributes including names, dates of birth, and ID numbers. Relationships vary (i.e., a student may only have one teacher but a single teacher may have several students).
  • Hospital Management Databases – Entities for this type of database include people (“Patients,” “Doctors,” and “Nurses”), as well as other tangibles, such as different hospital buildings and inventory. These databases can get very complex, with multiple relationships linking the various people involved to different buildings, treatment areas, and inventory.
  • E-Commerce Databases – People play an important role in the entities for e-commerce sites, too, because every site needs a list of customers. Those customers have payment details and order histories, which are potential entities or attributes. Product lists and available inventory are also factors.

Master the ER Model in DBMS


An ER diagram in DBMS can look like a complicated mass of shapes and lines at first, making them feel impenetrable to those new to databases. But once you get to grips with what each type of shape and line represents, they become crucial tools to help you outline your databases before you start developing them.


Application of what you’ve learned is the key to success with ER diagrams (and any other topic), so take what you’ve learned here and start experimenting. Consider real-world scenarios (such as those introduced above) and draw diagrams based on the entities you believe apply to those scenarios. Build up from there to figure out the attributes and relationships between entity sets and you’re well on your way to a good ER diagram.

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Metro: Is the AI bubble about to burst after Bank of England warns of dot-com crash repeat?
OPIT - Open Institute of Technology
OPIT - Open Institute of Technology
Oct 15, 2025 5 min read

Source:

  • Metro, published on October 09th, 2025

The Bank of England is ringing the bell over an ‘AI bubble’ that could burst at any moment – or maybe not, some experts told Metro.

By Josh Milton

After ChatGPT came on the scene in 2022, the tech industry quickly began comparing the arrival of AI to the dawn of the internet in the 1990s.

Back then, dot-com whizzes were minting easy millions only for the bubble to burst in 2000 when interest rates were hiked. Investors sold off their holdings, companies went bust and people lost their jobs.

Now central bank officials are worried that the AI industry may see a similar boom and bust.

record of the Financial Policy Committee’s October 2 meeting shows officials saying financial market evaluations of AI ‘appear stretched’.

‘This, when combined with increasing concentration within market indices, leaves equity markets particularly exposed should expectations around the impact of AI become less optimistic,’ they added.

AI-focused stocks are mainly in US markets but as so many investors across the world have bought into it, a fallout would be felt globally.

ChatGPT creator OpenAI, chip-maker Nvidia and cloud service firm Oracle are among the AI poster companies being priced big this year.

Earnings are ‘comparable to the peak of the dot-com bubble’, committee members said.

Factors like limited resources – think power-hungry data centres, utilities and software that companies are spending billions on – and the unpredictability of the world’s politics could lead to a drop in stock prices, called a ‘correction’.

In other words, the committee said, investors may be ignoring how risky AI technology is.

Metro spoke with nearly a dozen financial analysts, AI experts and stock researchers about whether AI will suffer a similar fate. There were mixed feelings.

‘Every bubble starts with a story people want to believe,’ says Dat Ngo, of the trading guide, Vetted Prop Firms.

‘In the late 90s, it was the internet. Today, it’s artificial intelligence. The parallels are hard to ignore: skyrocketing stock prices, endless hype and companies investing billions before fully proving their business models.

‘The Bank of England’s warning isn’t alarmist – it’s realistic. When too much capital chases the same dream, expectations outpace results and corrections follow.’

Dr Alessia Paccagnini, an associate Professor from the University College Dublin’s Michael Smurfit Graduate Business School, says that companies are spending £300billion annually on AI infrastructure, while shoppers are spending $12billion. That’s a big difference.

Tech firms listed in the US now represent 30% of New York’s stock index, S&P 500 Index, the highest proportion in 50 years.

‘As a worst-case scenario, if the bubble does burst, the immediate consequences would be severe – a sharp market correction could wipe trillions from stock valuations, hitting retirement accounts and pension funds hard,’ Dr Paccagnini adds.

‘In my opinion, we should be worried, but being prepared could help us avoid the worst outcomes.’

One reason a correction would be so bad is because of how tangled-up the AI world is, says George Sweeney, an investing expert at the personal finance website site Finder.

‘If it fails to meet the lofty expectations, we could see an almighty unravelling of the AI hype that spooks markets, leading to a serious correction,’ he says.

Despite scepticism, AI feels like it’s everywhere these days, from dog bowls and fridges to toothbrushes and bird feeders.

And it might continue that way for a while, even if not as enthusiastically as before, says Professor Filip Bialy, who specialises in computer science and AI ethics at the at Open Institute of Technology.

‘TAI hype – an overly optimistic view of the technological and economic potential of the current paradigm of AI – contributes to the growth of the bubble,’ he says.

‘However, the hype may end not with the burst of the bubble but rather with a more mature understanding of the technology.’

Some stock researchers worry that the AI boom could lose steam when the companies spending billions on the tech see profits dip.

The AI analytic company Qlik found that only one in 10 business say their AI initiatives are seeing sizeable returns.

Qlik’s chief strategy officer, James Fisher, says this doesn’t show that the hype for AI is bursting, ‘but how businesses look at AI is changing’.

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Everything You Need to Know to Join OPIT
OPIT - Open Institute of Technology
OPIT - Open Institute of Technology
Oct 13, 2025 6 min read

OPIT – Open Institute of Technology offers an innovative and exciting way to learn about technology. It offers a range of bachelor’s and master’s programs, plus a Foundation Year program for those taking the first steps towards higher education. Through its blend of instruction-based and independent learning, it empowers ambitious minds with the skills and knowledge needed to succeed.

This guide covers all you need to know to join OPIT and start your educational journey.

Introducing the Open Institute of Technology

Before we dig into the nitty-gritty of the OPIT application process, here’s a brief introduction to OPIT.

OPIT is a fully accredited Higher Education Institution under the European Qualification Framework (EQF) and the MFHEA Authority. It offers exclusively online education in English to an international community of students. With a winning team of top professors and a specific focus on computer science, it trains the technology leaders of tomorrow.

Some of the unique elements that characterize OPIT’s approach include:

  • No final exams. Instead, students undergo progressive assessments over time
  • A job-oriented, practical focus on the courses
  • 24/7 support, including AI assistance and student communities, so everyone feels supported
  • A strong network of company connections, unlocking doors for graduates

Reasons to Join OPIT

There are many reasons for ambitious students and aspiring tech professionals to study with OPIT.

Firstly, since all the study takes place online, it’s a very flexible and pleasant way to learn. Students don’t feel the usual pressures or suffer the same constraints they would at a physical college or university. They can attend from anywhere, including their own homes, and study at a pace that suits them.

OPIT is also a specialist in the technology field. It only offers courses focused on tech and computer science, with a team of professors and tutors who lead the way in these topics. This ensures that students get high-caliber learning opportunities in this specific sector.

Learning at OPIT is also hands-on and applicable to real-world situations, despite taking place online. Students are not just taught core skills and knowledge, but are also shown how to apply those skills and knowledge in their future careers.

In addition, OPIT strives to make technology education as accessible, inclusive, and affordable as possible. Entry requirements are relatively relaxed, fees are fair, and students from around the world are welcome here.

What You Need to Know About Joining OPIT

Now you know why it’s worth joining OPIT, let’s take a closer look at how to go about it. The following sections will cover how to apply to OPIT, entry requirements, and fees.

The OPIT Application Process

Unsurprisingly for an online-only institution, the application process for OPIT is all online, too. Users can submit the relevant documents and information on their computers from the comfort of their homes.

  1. Visit the official OPIT site and click the “Apply now” button to get started, filling out the relevant forms.
  2. Upload your supporting documents. These can include your CV, as well as certificates to prove your past educational accomplishments and level of English.
  3. Take part in an interview. This should last no more than 30 minutes. It’s a chance for you to talk about your ambitions and background, and to ask questions you might have about OPIT.

That’s it. Once you complete the above steps, you will be admitted to your chosen course and can start enjoying OPIT education once the first term begins. You’ll need to sign your admissions contract and pay the relevant fees, then begin classes.

Entry Requirements for OPIT Courses

OPIT offers a small curated collection of courses, each with its own requirements. You can consult the relevant pages on the official OPIT site to find out the exact details.

For the Foundation Program, for example, you simply need an MQF/EQF Level 3 or equivalent qualification. You also need to demonstrate a minimum B2 level of English comprehension.

For the BSc in Digital Business, applicants should have a higher secondary school leaving certificate, plus B2-level English comprehension. You can also support your application with a credit transfer from previous studies or relevant work experience.

Overall, the requirements are simple, and it’s most important for applicants to be ambitious and eager to build successful careers in the world of technology. Those who are driven and committed will get the best from OPIT’s instruction.

Fees and Flexible Payments at OPIT

As mentioned above, OPIT makes technological education accessible and affordable for all. Its tuition fees cover all relevant teaching materials, and there are no hidden costs or extras. The institute also offers flexible payment options for those with different budgets.

Again, exact fees vary depending on which course you want to take, so it’s important to consult the specific info for each one. You can pay in advance to enjoy 10% off the final cost, or refer a friend to also obtain a discount.

In addition to this, OPIT offers need-based and merit-based scholarships. Successful candidates can obtain discounts of up to 40% on bachelor’s and master’s tuition fees. This can substantially bring the term cost of each program down, making OPIT education even more accessible.

Credit Transfers and Experience

Those who are entering OPIT with pre-existing work experience or relevant academic achievements can benefit from the credit transfer program. This allows you to potentially skip certain modules or even entire semesters if you already have relevant experience in those fields.

OPIT is flexible and fair in terms of recognizing prior learning. So, as long as you can prove your credentials and experience, this could be a beneficial option for you. The easiest way to find out more and get started is to email the OPIT team directly.

Join OPIT Today

Overall, the process to join OPIT is designed to be as easy and stress-free as possible. Everything from the initial application forms to the interview and admission process is straightforward. Requirements and fees are flexible, so people in different situations and from different backgrounds can get the education they want. Reach out to OPIT today to take your first steps to tech success.

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