Hey, welcome back, everyone. Let's continue topic one in our database class with part six. And this video will provide an overview of database systems. And I want to highlight the word systems here because it speaks to an important point. And that is that the databases that we use are a part of larger organizational systems. So it's not just about the databases themselves or software that administer those databases, but there's a bigger picture. And if we genuinely want to have a good understanding of the role of databases in a modern organizational environment and the value that they bring to modern organizations, then we need to zoom out a little bit and try to understand these systems a little more holistically. Database systems then are comprised of four different components. And these are listed here. So we have users, people or machines. We have database applications. These are the things that we're all familiar with because whether we recognize it or not, we all use database applications almost every single day of our lives. These could be apps on your phone. They could be data-driven websites that you use. They could be software programs that you run on a desktop or laptop. Suffice it to say there are many database applications out there and we use them quite regularly. Number three, our third component of a database system is a DBMS or a database management system. And this is what most people think of when they say that they're working with a database. This is essentially a software program that controls the database. And we'll talk about this in much more detail. We'll see that the DBMS provides us with many capabilities. But for now, and we're talking about the actual where that six-width and controls databases, that is the database management system. And finally, the fourth element in our set of components for a database system are the databases themselves. This is where the data are actually stored. And as we learn last time, they have a structure and we'll study that a little more as we work our way through this class. For now, let me say that it's, if you're using any sort of enterprise-level database management system, then it is perfectly feasible to have more than one database being controlled and accessed by the single DBMS. So a DBMS can access work with, control, creates many different databases. So then just have to be one database. So many organizations will have multiple databases. Example might be that you have development database and you have a production database, or you may have operational database that controls the, or handles the transactional data, the day-to-day transactional data, and then you may have a data warehouse as a separate database that you use for analytics purposes. And all of these different types of databases can be controlled, accessed, and managed by a single DBMS. So here's a lovely graphical representation of the relationships among these four different components of a database system. And there are some important lessons to be learned by taking a look at a diagram such as the one shown here. First, I'd like to draw to your attention the fact that these four components of the database system are not allowed to interact. Each one of them is not allowed to interact with all of the other three elements. Each one can at most interact with two of these elements. So beginning over here on the left, we can talk about users and it's comfortable and familiar for us to think about users as human beings. So if you're using some sort of data-driven app on your phone, you're a user. If you're a human being and you're using a data-driven website, you are a user in the database system. And again, that's just a convenience. The reality in this modern world is that there are other types of users as well, non-human users. We have systems, machines that effectively act as users in this sequence of components that collectively comprise a database system as well. We don't limit your thinking to imagining users just as human beings. From a database design perspective, they could be human beings that they could also be machines. And the database management system is not going to distinguish between a human user and a machine user. Because our typical security model will just rely on something like a username and a password, which could be provided to the database either by a human or by some machine. Say by, I don't know, a machine outside of our organization. Many of these data-driven services now are deployed in the form of API's application programming interfaces. And in that case, we can have, say, our technology, our information systems can talk to and consume a resource or service that is provided by another organization. So in this case, it's an example of a machine user. I tend that that would be accessed via these application programming interfaces where APIs. And so users, humans or machines, keep your mind flexible on that point, our next component to consider here are these database applications. And these are the software programs that's on the one hand need to rely on a DBMS for the purpose of having a data storage layer. But on the front end are used by our users as a basis for accomplishing some sort of work-related task. Okay, so users are going to use database applications to accomplish something. And those database applications in turn are going to, as we see here, interact with our DBMS and use the underlying DBMS and underlying databases as a data layer where they can store information, retrieve necessary information, modify data, et cetera, for the purpose of allowing the users to accomplish. Whatever it is, they seek to accomplish their work tasks that recreational tasks through the use of these database applications. So from a work perspective, these can be desktop applications, maybe corporate systems that allow them to manage things like human resources payroll. Maybe these are web-based tools that rely on data in order to accomplish something like a manager or dashboards, e-commerce websites, news websites, things like Wikipedia. These are all data-driven web applications that would qualify as database applications. Similarly, the apps on your phone, many of them use databases in order to do things like store your preferences, or store account information, et cetera, related to whatever that app is intended to accomplish. So they qualify as database applications as well. Point is that we as users are using them to accomplish some sort of task, be it work-related, recreational about efficiency, helping us just to accomplish tasks in our non-work life and so on. Our third component then is the DBMS, the database management system. And this, as you can see, serves as a sort of gatekeeper for the data. So the data themselves, which are extraordinarily valuable corporate assets in many cases, are stored in a database. And as we can see here, it is only the DBMS that is allowed to communicate with the database, base applications, for example, are not allowed to communicate directly with the database users are not allowed to communicate directly with the database. It is only the DBMS that has that capability. And this is intentional in the sense that it provides us with a natural security barrier. Right? In order to get to the data, anything on the outside, users, database applications need to go through the DBMS. So the DBMS serves as a sort of line of defense, perimeter defense in our broader organizational security model for protecting our data, which again are some of typically or often are some of the organization's most valid assets. The data themselves can be further protected inside the database using techniques such as encryption, hashing, et cetera. So we have mechanisms for protecting the data in the database. So if someone is able, some malicious party is somehow able to get through the security layers that we have in place between users and our applications and get through the security layers that we have in between our database applications and the DBMS, as if they're able to breach the DBMS, then we can have additional mechanisms of protecting the data in the database by, for example, encrypting those data. And this layered security model is the gold standard. It's the model that is most widely used today. All right. So the DBMS serves as a gatekeeper. No one gets through the data base unless they go through the DBMS. So we then have this sort of chain or flows of information. You can imagine a user like you or me, maybe we're wanting to do some online shopping. So we decide to load up our web browser and go to Amazon. So Amazon is a web-based, bid-driven application. So we can send our requests through Amazon. Amazon can then, you know, as necessary, interact with the DBMS that has access to its underlying databases, that DBMS can then do whatever we need to do, pull data out of the database, make updates, record a new order, add a new mailing address, whatever we need to do, all those data would actually be manipulated or created here in the database. And then we get a reply back, maybe if we're doing a query, I don't know, show me all of the T-shirts that are on sale. Like that's a query. And so the answer is derived from the database, flows back through the DBMS to the database application, which in this case would be like the Amazon website. And then that is shown to us as users. In case we have these sort of information flows and we can see how they flow through these four various components of a database system.