Hey guys in this lesson, we will start looking at how we can go over reverse engineering our newly created database into a database model. Now a database model is a graphical representation of our tables and how they relate to each other in database development, terminologies really referred to as an entity relationship diagram or er D for short, or ER diagram, all of those are pretty much the same thing. And what you're seeing on screen here is an ER diagram that was generated based on one of the sample of this database is called World Alright, so this is essentially a graphical representation, like I said, off the database, meaning you print this out on a piece of paper and you hand it to somebody they should be able to clearly identify your table which is which is represented by this box here. And it's also called an entity so table and the entity are pretty much used interchangeably.

So the entity is city. And each line in this box represents the columns. And then you'll see that there's this highlighting thing that's going on here. And this line connecting city to country and also line connecting country language to country. So later in the lesson we will get into that those are called relationships, which is why the R means entity relationship diagram. So it shows the relationships between the tables.

We don't have any relationships in a school DB just yet. But we will be looking at how we can go about having already created our database using scripts reverse engineer into model looking form. So we're back on our home screen for my SQL workbench. In just opened it we land on this screen, and there are two avenues to get to this data modeling interface. So one, we can go ahead and create on a tour instance, like we would on a normal circumstances, and here I have all of the script files. So if you have closed the workbench and reopen, did you notice that it kind of keeps track of all the scripts that you would have been working on.

But that's besides the point. To get started with this reverse engineering, you could just go to database and then you see the option there that says reverse engineer. Alternatively, without even connecting to the instance, you could just go to this modeling this er D looking icon to the left, which is underneath that dolphin, right? And then you could go ahead and just click this arrow and then it will say create ER model from database. So either one of those ways can get you started. You also have that database option up here, reverse engineer, so any way you take it, it will be the same results.

So I just go ahead and click reverse engineer up here, and they both will launch this To this dialog, which will ask you to select an instance to connect to maybe yours would would have started off blank. So you can just click that. And you can just choose the default local instance that you would have been using to connect up to now, and everything would have been filled in, you click next, and then it will do some checks. And then it will ask you which one of these schemas Do you want to include? So you can do multiple schemas at a time. Or no, we're just focusing on the one that we're creating.

So I'll just click school dB, and click Next. There are some checks click Next. And then it will ask us what objects do we want to import. So the CRD actually will import all the tables, all the views, all the function and stored procedures that are in your database in total, so right now we only have some tables, which are courses, lecturers and students and by default, the tables will be included. Alright, so we can just go ahead and click Execute. So they say that the three are selected.

If you want to deselect or not choose one, you can just click it and click that arrow and it will bring it over. So it will know that three are in total. And two have been selected for the modeling exercise. But I want all three in the modeling exercise, so I'll just leave that as it is. And then I'll go ahead and click Execute. And then this will do something in the background, which I really want to see.

So I just click next, and get rid of this on the screen by clicking finish. And I see here that Okay, I have one table somewhere, and then you can have a visual cue as to where your tables are on the sheet of paper. So as you scroll down, you'll see that the next one is there and as you move it, the visual cue is updating. So I want to see all three of them beside each other. So I just dragged all of them up to the top. And you would notice once again that we have no lines because we haven't established any relationships between our tables.

Just yet, we will get there. But I just really wanted to show you that my SQL workbench makes it easy that having created the database, if your supervisor wants to see it on paper, you know, he doesn't want to go into the database and log in to see Oh, you did this and that how what are the rules. So this is a nice easy way to just represent your database that your supervisor who might be it savvy, or your manager who might not be it so we can have an appreciation for your database design and all the entities and the columns or data points that you are storing per entity. Also, you would notice that the icons are there representing the primary keys and they are color coded according to when we were initially designing this database. So we can have some visual cues as to what is nullable and what is not.

Now the cool thing about this is that you can also make changes here you can actually add a new table on to this onto this sheet right here. So I can just say table one. And I can start putting in all the columns just like we did when we're designing or tables. Using the workbench interface, we can make all those modifications, and then effect those changes in the database. So you have some people who aren't so first on using the script to design their database. So they rely on the data data modeling tool, provided by workbench, which allows them to just click and put in the data and then have this visual representation, and then the generate the database from the already generated model.

In this case, we already built our database and now we're just looking at the model for it. But later on in this lesson, we will be looking at how we can go about generating the database from a model that is designed in this interface.