In a database, you have entities (which have attributes), and relationships between those entities. Managing them is key to preventing chaos from engulfing your database, which is where the concept of keys comes in. These unique identifiers enable you to pick specific rows in an entity set, as well as define their relationships to rows in other entity sets, allowing your database to handle complex computations.


Let’s explore keys in DBMS (database management systems) in more detail, before digging into everything you need to know about the most important keys – primary keys.


Understanding Keys in DBMS


Keys in DBMS are attributes that you use to identify specific rows inside a table, in addition to finding the relation between two tables. For example, let’s say you have a table for students, with that table recording each student’s “ID Number,” “Name,” “Address,” and “Teacher” as attributes. If you want to identify a specific student in the table, you’ll need to use one of these attributes as a key that allows you to pull the student’s record from your database. In this case “ID Number” is likely the best choice because it’s a unique attribute that only applies to a single student.


Types of Keys in DBMS


Beyond the basics of serving as unique identifiers for rows in a database, keys in DBMS can take several forms:


  • Primary Keys – An attribute that is present in the table for all of the records it contains, with each instance of that attribute being unique to the record. The previously-mentioned “ID Number” for students is a great example, as no student can have the same number as another student.
  • Foreign Key – Foreign keys allow you to define and establish relationships between a pair of tables. If Table A needs to refer to the primary key in Table B, you’ll use a foreign key in Table A so you have values in that table to match those in Table B.
  • Unique Key – These are very similar to primary keys in that both contain unique identifiers for the records in a table. The only difference is that a unique key can contain a null value, whereas a primary key can’t.
  • Candidate Key – Though you may have picked a unique attribute to serve as your primary key, there may be other candidates within a table. Coming back to the student example, you may record the phone numbers and email addresses of your students, which can be as unique as the student ID assigned to the individual. These candidate keys are also unique identifiers, allowing them to be used in tandem with a primary key to identify a specific row in a table.
  • Composite Key – If you have attributes that wouldn’t be unique when taken alone, but can be combined to form a unique identifier for a record, you have a composite key.
  • Super Key – This term refers to the collection of attributes that uniquely identify a record, meaning it’s a combination of candidate keys. Just like an employer sifting through job candidates to find the perfect person, you’ll sift through your super key set to choose the ideal primary key amongst your candidate keys.

So, why are keys in DBMS so important?


Keys ensure you maintain data integrity across all of the tables that make up your database. Without them, the relationships between each table become messy hodgepodges, creating the potential for duplicate records and errors that deliver inaccurate reports from the database. Having unique identifiers (in the form of keys) allows you to be certain that any record you pull, and the relationships that apply to that record, are accurate and unrepeated.



Primary Key Essentials


As mentioned, any unique attribute in a table can serve as a primary key, though this doesn’t mean that every unique attribute is a great choice. The following characteristics help you to define the perfect primary key.


Uniqueness


If your primary key is repeatable across records, it can’t serve as a unique identifier for a single record. For example, our student table may have multiple people named “John,” so you can’t use the “Name” attribute to find a specific student. You need something unique to that student, such as the previously mentioned ID number.


Non-Null Values


Primary keys must always contain a value, else you risk losing records in a table because you have no way of calling upon them. This need for non-null values can be used to eliminate some candidates from primary key content. For instance, it’s feasible (though unlikely) that a student won’t have an email address, creating the potential for null values that mean the email address attribute can’t be a primary key.


Immutability


A primary key that can change over time is a key that can cause confusion. Immutability is the term used for any attribute that’s unchanging to the point where it’s an evergreen attribute that you can use to identify a specific record forever.


Minimal


Ideally, one table should have one attribute that serves as its primary key, which is where the term “minimal” comes in. It’s possible for a table to have a composite or super key set, though both create the possibility of confusion and data integrity issues.


The Importance of a Primary Key in DBMS


We can distill the reason why having a primary key in DBMS for each of your tables is important into the following reasons:


  • You can use a primary key to identify each unique record in a table, meaning no multi-result returns to your database searches.
  • Having a primary key means a record can’t be repeated in the table.
  • Primary keys make data retrieval more efficient because you can use a single attribute for searches rather than multiple.

Functions of Primary Keys


Primary keys in DBMS serve several functions, each of which is critical to your DBMS.


Data Identification


Imagine walking into a crowded room and shouting out a name. The odds are that several people (all of whom have the same name) will turn their heads to look at you. That’s basically what you’re doing if you try to pull records from a table without using a primary key.


A primary key in DBMS serves as a unique identifier that you can use to pull specific records. Coming back to the student example mentioned earlier, a “Student ID” is only applicable to a single student, making it a unique identifier you can use to find that student in your database.


Ensure Data Integrity


Primary keys protect data integrity in two ways.


First, they prevent duplicate records from building up inside a single table, ensuring you don’t get multiple instances of the same record. Second, they ensure referential integrity, which is the term used to describe what happens when one table in your database needs to refer to the records stored in another table.


For example, let’s say you have tables for “Students” and “Teachers” in your database. The primary keys assigned to your students and teachers allow you to pull individual records as needed from each table. But every “Teacher” has multiple “Students” in their class. So, your primary key from the “Students” table is used as a foreign key in the “Teachers” table, allowing you to denote the one-to-many relationship between a teacher and their class of students. That foreign key also ensures referential integrity because it contains the unique identifiers for students, which you can look up in your “Students” table.


Data Retrieval


If you need to pull a specific record from a table, you can’t rely on attributes that can repeat across several records in that table. Again, the “Name” example highlights the problem here, as several people could have the same name. You need a unique identifier for each record so you can retrieve a single record from a huge set without having to pore through hundreds (or even thousands) of records.


Best Practices for Primary Key Selection


Now that you understand how primary keys in DBMS work, here are some best practices for selecting the right primary key for your table:


  • Choose Appropriate Attributes as Candidates – If the attribute isn’t unique to each record, or it can contain a null value (as is the case with email addresses and phone numbers), it’s not a good candidate for a primary key.
  • Avoid Using Sensitive Information – Using personal or sensitive information as a primary key creates a security risk because anybody who cracks your database could use that information for other purposes. Make your primary keys unique, and only applicable, to your database, which allows you to encrypt any sensitive information stored in your tables.
  • Consider Surrogate Keys – Some tables don’t have natural attributes that you can use as primary keys. In these cases, you can create a primary key out of thin air and assign it to each record. The “Student ID” referenced earlier is a great example, as students entering a school don’t come with their own ID numbers. Those numbers are given to the student (or simply used in the database that collects their data), making them surrogate keys.
  • Ensure Primary Key Stability – Any attribute that can change isn’t suitable for use as a primary key because it causes stability issues. Names, email addresses, phone numbers, and even bank account details are all things that can change, making them unsuitable. Evergreen and unchanging is the way to go with primary keys.

Choose the Right Keys for Your Database


You need to understand the importance of a primary key in DBMS (or multiple primary keys when you have several tables) so you can define the relationships between tables and identify unique records inside your tables. Without primary keys, you’ll find it much harder to run reports because you won’t feel confident in the accuracy of the data returned. Each search may pull up duplicate or incorrect records because of a lack of unique identifiers.


Thankfully, many of the tables you create will have attributes that lend themselves well to primary key status. And even when that isn’t the case, you can use surrogate keys in DBMS to assign primary keys to your tables. Experiment with your databases, testing different potential primary keys to see what works best for you.

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The Path to Education Is Not Always Straightforward
OPIT - Open Institute of Technology
OPIT - Open Institute of Technology
Dec 17, 2025 6 min read

Life is unpredictable. While many of us have specific hopes and expectations of how our futures will turn out, things don’t always go as expected. There are many variables and unexpected incidents that can interfere and force you to alter your plans, and this is particularly true when it comes to education.

For instance, you might have had plans to study a specific subject, but had to deviate from those plans due to unforeseen circumstances. Or you may have had to enter the workforce in an occupation different from the one you sought in an effort to earn an income, a move that may not provide you with the time or opportunity to achieve your desired educational aims.

In short, every individual’s career pathway is different, and very few go exactly as we expect from the outset. Fortunately, even if you experience a few false starts or sudden twists in your pathway, there are always options available to help you get back on track.

The Unpredictable Nature of Education

In theory, the educational process seems simple. You select a course of study that interests you from the vast array of subjects and prospective professions, select the appropriate classes, acquire the knowledge and skills you need to succeed, and then embark on your profession.

In reality, however, as many people know from firsthand experience, the road to education is often far from straightforward. Here are just some of the many challenges that can take your educational path in a completely different direction:

  • Life’s Curveballs: As touched on in the introduction, life is impossible to predict. Financial hardships, health issues, and family emergencies are just some of the unfortunate occurrences that might derail even the most perfectly planned educational regime.
  • Changing Interests: People’s desires and preferences don’t necessarily stay the same throughout their entire lives. As you grow, learn, and have new experiences, your interests may change, and so, too, may your educational objectives.
  • Pressure and Burnout: Some academic paths are particularly challenging, demanding intense levels of study and hard work. This can sometimes prove too much to bear, even for the most resilient students.
  • Failures and Setbacks: Conventional education largely builds around tests and examinations, requiring students to demonstrate their competencies repeatedly. It’s a system that doesn’t suit everyone, and test failures can lead to setbacks and delays.
  • Inequality: People can be born with very different privileges and levels of access to education. Those in certain parts of the world may find it much more challenging to complete their education path for financial, cultural, or even political reasons.
  • Late Bloomers: People develop at different paces. Some may struggle educationally early on in their lives, forcing them to make certain concessions or sacrifices related to their studies, only to find their feet later in life once they’ve entered the world of work.

Whether you’re a late bloomer, have had your educational aspirations delayed by personal problems, desire to learn new skills and try something different, or want to begin a fresh chapter in your professional life, the Open Institute of Technology (OPIT) may be able to help.

Introducing OPIT

OPIT is an online teaching platform, making high-level technological educational programs accessible to all, no matter their age or background. Offering education in fields like computer science, artificial intelligence, and digital business, OPIT provides a curated collection of degrees. In addition, they offer classes taught by world-leading tutors imparting the wisdom and skills students need to achieve their goals and become the tech leaders of tomorrow.

Meanwhile, for those who have had somewhat tumultuous or unpredictable educational paths, OPIT offers the perfect course corrector: the OPIT Foundation Year.

The OPIT Foundation Year

OPIT’s Foundation Year is a Pre-Tertiary Certificate in Information Technology, fully aligned with MQF/EQF Level 4 standards and valued at 60 ECTS credits. Lasting just one year, this program essentially serves as a comprehensive yet accessible springboard towards higher-level education, creating a path towards degrees and careers in dynamic, flexible fields, like computer science and digital business.

Like other OPIT programs, the Foundation Year is delivered entirely online via the OPIT Virtual Learning Environment. Combining live lectures, asynchronous content, and interactive assessments, students enjoy diverse and dynamic study experiences, acquiring core skills like academic writing, mathematics, and computer literacy, and building a bedrock of knowledge and confidence before taking their next steps.

Who Is the Foundation Program For?

The Foundation Program is designed to provide a solid base upon which to build the technological education many students need. It’s the perfect choice for those who are eager and ambitious to enter professions in AI, data science, and computing, but don’t feel that they have the necessary core skills and knowledge needed to dive straight into a degree.

Entry requirements are relatively relaxed in order to allow as many students as possible to enjoy the benefits of this program. With that said, applicants should ideally hold an MQF/EQF Level 3 or equivalent qualification, with the intention of pursuing a bachelor’s degree. A minimum of B2 level of English proficiency is also required, as this is the working and studying language of the institution.

What the Foundation Year Provides

Perhaps you’ve recently graduated, are considering a career change, or finally have the opportunity to return to education after initial delays or unexpected disruptions to your original plans. Either way, the Foundation Year can help you enjoy:

  • Greater Self-Confidence: Foundation Year graduates gain the fundamental skills they need to enter degree programs with much more self-belief and assuredness.
  • Superior Tech Knowledge: Lasting two terms, this course explores mathematics, academic reading and writing, and provides an introduction to computer hardware and software.
  • Foundational Mathematics: Mathematics literacy forms a large part of the study focus for the Foundation Year, helping students feel more comfortable with numbers and formulas.
  • Flexible Learning: Unlike more rigid, conventional education environments, OPIT gives you the freedom and flexibility to study at a pace that suits you best, all from the comfort of home.
  • Global Community: OPIT is an international institution, with staff and students from all around the world eager to share knowledge, exchange ideas, and help one another.

Take Your Next Steps to Success With the OPIT Foundation Year

If you’re curious about a career in technology or have always wanted to work with AI, data, and computers, but struggled to find the time and opportunities you need to acquire relevant skills and knowledge, the Foundation Program was made for people like you.

It’s the ideal entry point into the exciting world of online education, and the perfect first step towards a prestigious degree from an innovative and increasingly successful institution. Download the brochure to learn more about it, or start your online application, today.

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Benefits of Doing a Career in Computer Science
OPIT - Open Institute of Technology
OPIT - Open Institute of Technology
Dec 17, 2025 6 min read

Students today have a broader range of fields of study to choose from than ever before, but with the world becoming increasingly technological and computers increasing in influence and importance, pursuing a career in computer science often proves a smart, strategic choice.

There are numerous benefits and career paths associated with studying and working in computer science, and we’ll be listing just a few of them in this guide.

High Average Salaries

With the rising cost of living in many parts of the world, it’s unsurprising that many students are thinking several decades ahead to determine what level of starting salaries they could obtain in different career fields.

Many are also seeking professions that offer the opportunity for growth and the ability to advance up the ranks over time, thus increasing their salary and their quality of life in the process.

If a strong, stable salary with the opportunity for improved income is one of your top career priorities, computer science should be at or near the top of your list of prospective careers.

According to recent data, computer scientists earn an average of over €65,000 per year, with certain jobs, like IT project leader and data scientist, paying ever higher. Starting salaries are strong, too, with graduates earning anywhere from €46,000 to €60,000, depending on their chosen profession and level of qualifications.

There are similarly high average salaries reported around the world in computer science and related fields such as data science and AI/ML engineering. These numbers are projected to increase in the years to come, pointing to computer science as a way for graduates to get off to the best financial start of any career.

Unrivaled Flexibility

A common problem with some subjects and courses is that they only provide graduates with a narrow set of skills and a similarly narrow range of potential professions to which they can apply those skills.

That’s not the case with computer science. Graduates in this field can enjoy instant access to a remarkably diverse array of career opportunities, with even newer opportunities being created all the time as technology evolves and innovations emerge.

A few of the many industries and roles you might choose to enter in the field of computer science include:

  • Healthcare: As a software developer, data analyst, or cybersecurity expert
  • Finance: As a fintech engineer, blockchain developer, or security analyst
  • Media: As a graphics programmer, AI developer, or game developer
  • Education: As an analyst, software developer, or machine learning engineer

Guaranteed Opportunities

Some career paths are more limited than others, with relatively low numbers of opportunities, recurring risks of job loss, or difficulty obtaining employment in the first place.

Again, with computer science, this simply isn’t the case. At a time when 75% of companies plan to embrace AI and other technologies by 2027, and businesses of all sizes and industries are now relying on computers more than ever before, computer science graduates can enjoy almost unbeatable job security.

Opportunities will continue to grow for people with good computing knowledge, whether that be in the obvious fields like software and web development, engineering, and AI development, or more niche sectors.

With so many options, you’re effectively guaranteed a long, rewarding career if you put in the necessary time and effort needed to establish a strong foundation of computing skills.

Rapidly Expanding and Evolving Industries

It’s no secret that the world of technology is a dynamic and fast-moving one. In the past 20 years alone, we’ve seen the proliferation of the internet, the rapid advancement of smartphones and wearable devices, the emergence of AI, and so much more.

In the years ahead, engineers and developers will continue to explore the boundaries of modern technology’s powers and potential, driving new innovations and improvements and opening more exciting job opportunities for those already established and experienced in this field.

Getting into computer science now could therefore provide a solid foundation for a career filled with excitement as you uncover and explore new ways of working with computers in fields as diverse as healthcare, finance, education, entertainment, manufacturing, logistics, and beyond.

Start Your Computer Science Career at OPIT

We’ve discussed some of the many benefits associated with careers in computer science, from the high starting salaries to the rapidly growing array of job options available to graduates. By now, you may be eager to follow this particular career path and take advantage of the wealth of opportunities.

If you’re wondering how to start, the Open Institute of Technology (OPIT) may hold the answers you need. As an exclusively online learning platform, specializing in computer science and digital business, and staffed by some of the world’s leading tech experts, OPIT is producing the tech leaders of tomorrow.

Some of the many advantages of learning with OPIT include:

  • Accessible and flexible online education that matches your learning style and schedule
  • Heavy focus on real-world applications of the skills you acquire
  • An international community of like-minded students from around the globe
  • A top team of tutors and lecturers from varying fields and industries
  • Progressive assessment of skills and understanding – not constant exams

OPIT offers a small, curated selection of courses for those seeking to gain the technological skills and knowledge to succeed in their chosen areas of expertise. That includes a BSc (Hons) in Computer Science – a six-term program, worth 180 ECTS credits.

Numerous IT industry leaders and experts helped develop this fully accredited undergraduate degree, which is online and accessible to all. Like other OPIT courses, it offers a flexible learning program, with progressive assessments, fast-track options, and the opportunity to be part of a growing community of learners and tutors.

If the benefits of doing a career in computer science interest you, download the OPIT BSc in Computer Science brochure or fill out an online application today and take your first step toward a rewarding and fulfilling profession.

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