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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OPIT Program Deep Dive: BSc in Computer Science
OPIT - Open Institute of Technology
OPIT - Open Institute of Technology
Feb 6, 2026 6 min read

Computer Science is fast becoming one of the most valuable fields of study, with high levels of demand and high-salaried career opportunities for successful graduates. If you’re looking for a flexible and rewarding way to hone your computing skills as part of a supportive global community, the BSc in Computer Science at the Open Institute of Technology (OPIT) could be the perfect next step.

Introducing the OPIT BSc in Computer Science

The OPIT BSc in Computer Science is a bachelor’s degree program that provides students with a comprehensive level of both theoretical and practical knowledge of all core areas of computer science. That includes the likes of programming, databases, cloud computing, software development, and artificial intelligence.

Like other programs at OPIT, the Computer Science BSc is delivered exclusively online, with a mixture of recorded and live content for students to engage with. Participants will enjoy the instruction of world-leading lecturers and professors from various fields, including software engineers at major tech brands and esteemed researchers, and will have many paths open to them upon graduation.

Graduates may, for example, seek to push on with their educational journeys, progressing on to a specialized master’s degree at OPIT, like the MSc in Digital Business and Innovation or the MSc in Responsible Artificial Intelligence. Or they could enter the working world in roles like software engineer, data scientist, web developer, app developer, or cybersecurity consultant.

The bullets below outline the key characteristics of this particular course:

  • Duration: Three years in total, spread across six terms.
  • Content: Core courses for the first four terms, a student-selected specialization for the fifth term, and a capstone project in the final term.
  • Focus: Developing detailed theoretical knowledge and practical skills across all core areas of modern computer science.
  • Format: Entirely online, with a mixture of live lessons and asynchronous content you can access 24/7 to learn at your own pace.
  • Assessment: Progressive assessments over the course of the program, along with a capstone project and dissertation, but no final exams.

What You’ll Learn

Students enrolled in the BSc in Computer Science course at OPIT will enjoy comprehensive instruction in the increasingly diverse sectors that fall under the umbrella of computer science today. That includes a close look at emerging technologies, like AI and machine learning, as well as introductions to the fundamental skills involved in designing and developing pieces of software.

The first four terms are the same for all students. These will include introductions to software engineering, computer security, and cloud computing infrastructure, as well as courses focusing on the core skills that computer scientists invariably need in their careers, like project management, quality assurance, and technical English.

For the fifth term, students will have a choice. They can select five electives from a pool of 27, or select one field to specialize in from a group of five. You may choose to specialize in all things cybersecurity, for example, and learn about emerging cyber threats. Or you could focus more on specific elements of computer science that appeal to your interests and passions, such as game development.

Who It’s For

The BSc in Computer Science program can suit a whole range of prospective applicants and should appeal to anyone with an interest or passion for computing and a desire to pursue a professional career in this field. Whether you’re seeking to enter the world of software development, user experience design, data science, or another related sector, this is the course to consider.

In addition, thanks to OPIT’s engaging, flexible, and exclusively online teaching and learning systems, this course can appeal to people from all over the globe, of different ages, and from different walks of life. It’s equally suitable for recent high school graduates with dreams of making their own apps to seasoned professionals looking to broaden their knowledge or transition to a different career.

The Value of the BSc in Computer Science Course at OPIT

Plenty of universities and higher education establishments around the world offer degrees in computer science, but OPIT’s program stands out for several distinctive reasons.

Firstly, as previously touched upon, all OPIT courses are delivered online. Students have a schedule of live lessons to attend, but can also access recorded content and digital learning resources as and when they choose. This offers an unparalleled level of freedom and flexibility compared to more conventional educational institutions, putting students in the driving seat and letting them learn at their own pace.

OPIT also aims not merely to impart knowledge through lectures and teaching, but to actually help students gain the practical skills they need to take the next logical steps in their education or career. In other words, studying at OPIT isn’t simply about memorizing facts and paragraphs of text; it’s about learning how to apply the knowledge you gain in real-world settings.

OPIT students also enjoy the unique benefits of a global community of like-minded students and world-leading professors. Here, distance is no barrier, and while students and teachers may come from completely different corners of the globe, all are made to feel welcome and heard. Students can reach out to their lecturers when they feel the need for guidance, answers, and advice.

Other benefits of studying with OPIT include:

  • Networking opportunities and events, like career fairs, where you can meet and speak with representatives from some of the world’s biggest tech brands
  • Consistent support systems from start to finish of your educational journey in the form of mentorships and more
  • Helpful tools to expedite your education, like the OPIT AI Copilot, which provides personalized study support

Entry Requirements and Fees

To enroll in the OPIT BSc in Computer Science and take your next steps towards a thrilling and fulfilling career in this field, you’ll need to meet some simple criteria. Unlike other educational institutions, which can impose strict and seemingly unattainable requirements on their applicants, OPIT aims to make tech education more accessible. As a result, aspiring students will require:

  • A higher secondary school leaving certificate at EQF Level 4, or equivalent
  • B2-level English proficiency, or higher

Naturally, applicants should also have a passion for computer science and a willingness to study, learn, and make the most of the resources, community, and support systems provided by the institute.

In addition, if you happen to have relevant work experience or educational achievements, you may be able to use these to skip certain modules or even entire terms and obtain your degree sooner. OPIT offers a comprehensive credit transfer program, which you can learn more about during the application process.

Regarding fees, OPIT also stands out from the crowd compared to conventional educational institutions, offering affordable rates to make higher tech education more accessible. There are early bird discounts, scholarship opportunities, and even the option to pay either on a term-by-term basis or a one-off up-front fee.

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OPIT Program Deep Dive: Foundation Year
OPIT - Open Institute of Technology
OPIT - Open Institute of Technology
Feb 6, 2026 6 min read

The Open Institute of Technology (OPIT) provides a curated collection of courses for students at every stage of their learning journey, including those who are just starting. For aspiring tech leaders and those who don’t quite feel ready to dive directly into a bachelor’s degree, there’s the OPIT Foundation Program. It’s the perfect starting point to gain core skills, boost confidence, and build a solid base for success.

Introducing the OPIT Foundation Year Program

As the name implies, OPIT’s Foundation Program is about foundation-level knowledge and skills. It’s the only pre-bachelor program in the OPIT lineup, and successful students on this 60-ECTS credit course will obtain a Pre-Tertiary Certificate in Information Technology upon its completion. From there, they can move on to higher levels of learning, like a Bachelor’s in Digital Business or Modern Computer Science.

In other words, the Foundation Program provides a gentle welcome into the world of higher technological education, while also serving as a springboard to help students achieve their long-term goals. By mixing both guided learning and independent study, it also prepares students for the EQF Level 4 experiences and challenges they’ll face once they enroll in a bachelor’s program in IT or a related field.

Here’s a quick breakdown of what the OPIT Foundation Program course involves:

  • Duration: Six months, split into two terms, with each term lasting 13 weeks
  • Content: Three courses per term, with each one worth 10 ECTS credits, for a total of 60
  • Focus: Core skills, like mathematics, English, and introductory-level computing
  • Format: Video lectures, independent learning, live sessions, and digital resources (e-books, etc.)
  • Assessment: Two to three assessments over the course of the program

What You’ll Learn

The OPIT Foundation Program doesn’t intensely focus on any one particular topic, nor does it thrust onto you the more advanced, complicated aspects of technological education you would find in a bachelor’s or master’s program. Instead, it largely keeps things simple, focusing on the basic building blocks of knowledge and core skills so that students feel comfortable taking the next steps in their studies.

It includes the following courses, spread out across two terms:

  • Academic Skills
  • Mathematics Literacy I
  • Mathematics Literacy II
  • Internet and Digital Technology
  • Academic Reading, Writing, and Communication
  • Introduction to Computer Hardware and Software

Encompassing foundational-level lessons in digital business, computer science, and computer literacy, the Foundation Program produces graduates with a commanding knowledge of common operating systems. Exploring reading and writing, it also helps students master the art of communicating their ideas and responses in clear, academic English.

Who It’s For

The Foundation Year program is for people who are eager to enter the world of technology and eventually pursue a bachelor’s or higher level of education in this field, but feel they need more preparation. It’s for the people who want to work on their core skills and knowledge before progressing to more advanced topics, so that they don’t feel lost or left behind later on.

It can appeal to anyone with a high school-level education and ambitions of pushing themselves further, and to anyone who wants to work in fields like computer science, digital business, and artificial intelligence (AI). You don’t need extensive experience or qualifications to get started (more on that below); just a passion for tech and the motivation to learn.

The Value of the Foundation Program

With technology playing an increasingly integral role in the world today, millions of students want to develop their tech knowledge and skills. The problem is that technology-oriented degree courses can sometimes feel a little too complex or even inaccessible, especially for those who may not have had the most conventional educational journeys in the past.

While so many colleges and universities around the world simply expect students to show up with the relevant skills and knowledge to dive right into degree programs, OPIT understands that some students need a helping hand. That’s where the Foundation Program comes in – it’s the kind of course you won’t find at a typical university, aimed at bridging the gap between high school and higher education.

By progressing through the Foundation Program, students gain not just knowledge, but confidence. The entire course is aimed at eliminating uncertainty and unease. It imbues students with the skills and understanding they need to push onward, to believe in themselves, and to get more value from wherever their education takes them next.

On its own, this course won’t necessarily provide the qualifications you need to move straight into the job market, but it’s a vital stepping stone towards a degree. It also provides numerous other advantages that are unique to the OPIT community:

  • Online Learning: Enjoy the benefits of being able to learn at your own pace, from the comfort of home, without the costs and inconveniences associated with relocation, commuting, and so on.
  • Strong Support System: OPIT professors regularly check in with students and are on hand around the clock to answer queries and provide guidance.
  • Academic Leaders: The OPIT faculty is made up of some of the world’s sharpest minds, including tech company heads, experienced researchers, and even former education ministers.

Entry Requirements and Fees

Unlike OPIT’s other, more advanced courses, the Foundation Program is aimed at beginners, so it does not have particularly strict or complex entry requirements. It’s designed to be as accessible as possible, so that almost anyone can acquire the skills they need to pursue education and a career in technology. The main thing you’ll need is a desire to learn and improve your skills, but applicants should also possess:

  • English proficiency at level B2 or higher
  • A Secondary School Leaving Certificate, or equivalent

Regarding the fees, OPIT strives to lower the financial barrier of education that can be such a deterrent in conventional education around the world. The institute’s tuition fees are fairly and competitively priced, all-inclusive (without any hidden charges to worry about), and accessible for those working with different budgets.

Given that all resources and instruction are provided online, you can also save a lot of money on relocation and living costs when you study with OPIT. In addition, applicants have the option to pay either up front, with a 10% discount on the total, or on a per-term basis, allowing you to stretch the cost out over a longer period to ease the financial burden.

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