What's a Database

Many of you have probably heard the term database before, and maybe even have some concept of what a database is. I feel like it's one of those terms though that we throw around — oh yeah, it's a database server — but don't always understand fully what a database is. So we're going to cover the basics of what a database server is.

A Database Server Compared to a File Server

One thing I'm going to do is compare and contrast a database server to what a file server is. A file server is when we want to set up file sharing on a network. We have files and folders that we want to share out to the rest of the network, so we set up a machine to be a file server that's going to host those files for other machines on the network. Essentially we have files and folders that we want to share, so we have a machine that's going to share those out to other machines on the network.

A database server is somewhat similar, except it's not sharing out files and folders; that's not the purpose of it. Instead, a database server holds a bunch of data, and that data then can be shared out to other machines on the network, or perhaps servers on the network.

What a Database Server Does

For one, it gives us access to data. If we're on a machine right here, we would connect to the database server and then access the data of that database server.

Another thing that a database server does for us is it helps us interpret the data. We can pull certain reports, we do what's called a query and then pull data and compile data, so that it gives us data in certain formats so we can make conclusions from it. It helps relate different data points, so it can take data from these different areas and put it all together and help display it to us in a certain way.

It also provides redundancy. We can create redundancy with database servers that helps make sure that it has high availability, so if something goes down, one of these servers goes down, we still have access to that data, and that can be really important.

Also, for the data itself, it can provide structure for that data. We have something called a relational database, and that relational database will set up a structure so that we can store the data in some sort of structure.

Then it also helps manage all of the data and the services that are happening. For instance, we want to perform backup on our data to make sure that we have it and we don't lose it, and so a database server can help us perform those backups and other management tasks for this data.

Databases, Tables and Records

A database server can have many different databases that it's hosting, and those databases could have many different tables, and those tables could have many different records to it.

Here's an example of what a table is. A table has different columns; we've got employee ID, last name, first name, work phone. This is a Google Sheets table, and what we have right here is each row would be considered a record. So a database has multiple tables just like this, and within those tables it has different records, which would be each row. Essentially in this case it would be an employee per row, so an employee would be a record.

One type of database is called a relational database. That means that you have all of these different tables, but there's information within these tables that relate to each other. We use this for things like transactions, where you would have an employee, or perhaps maybe it's a customer and a list of customers that you have in one table, with all of the products that they're purchasing on another table, that would be grouped up in this table right here for every sale that they do. Relational databases can get pretty complex, so this is a very simplistic explanation, but essentially you have lots of tables that are interconnected, that are related to each other.

Database Commands

One way we get information into a database, and then are able to extract data out of a database, is through database commands. We would be on a machine where we would send database commands, and then the database would go and extract that information and give it to us, or input the data into its database. One thing that a database does is allow us to interact with this data through these database commands. One example of that is the structured query language, or SQL. SQL is the commands that we submit to the database server so that we can either extract or input data into the system.

An Example Setup

Let's see an example of how we use database servers. I'm just going to give you one example. Here we have a client right here and they want to access a website, so they're going to connect into web services. These are web services, and maybe it's running something like Apache, or maybe it's running some other system here. Essentially what happens a lot of times is we have a database server that's running on these machines that is providing some services and some data to the end client, and then the Apache server is accessing those databases.

But a lot of times we also separate out the database so it's its own machine on the back end. So now we have the database servers, we have the web servers, and we have the client. What happens is the client is interacting with the web servers, and then the web servers are accessing the database. One of the ways that this really helps out is that now these web servers can be redundant. We have three web servers right here that are providing web services for this client, or for all of the clients, whoever's connecting to it, but they're all running off this same data, the data on the back end, this database server on the back end. So it doesn't matter really which server you connect to, because they're all using the same data to deliver their services.

Ultimately, us as users are really used to dealing with files and folders, and if we were to set up sharing on our network, on our home networks, we probably want to share out files and folders. But there is a large number of databases that are out there, because a large amount of what we have is just data: data that needs to be structured, data that needs to be managed, data that we need to pull from and be able to put into and compile reports and all sorts of stuff. So there's a large amount of databases that are running out there that help us perform all of these IT functions and all of these services.