Introduction to Databases and SQL

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TRANSCRIPT

Hello everybody, and in this video, I want to give you an overview of what databases are and a little bit about the database, that we'll be using and then towards the end, we'll have a little experiment, that shows you, should hopefully enforce the point as to why using databases is useful, as opposed to storing data in some other kind of medium, like a text or Excel. So first of all is what is a database? Well, a database is a very efficient way to store highly structured data for querying and in data management. So what I mean by querying is really just question answering, so I have a ton of data and I wanna ask a question about it, what's a good way to do that and so that's a very high level definition, that I gave there, maybe a more concrete thing to do would be to equate databases to spreadsheets, so I have an example of an Excel workbook set up here and so you can conceptually think of the data stored inside of a database as being kind of like in a workbook like this, so it is a workbook, we have these different, down here at the bottom, you can see, we have different sheets here, so I have one sheet that says Track, I can go to another sheet, that says Album, let me make that a bit larger, we can see that, so I have another Track that has all of the albums here and then I can go back to Track, so these are two different sheets and in database lingo, these would be considered two different tables and again, they're even organized kind of conceptually in the fact that they look kind of like a table, here, let me make this a bit bigger.

So you know, we have a header row here, that tells me what each of the entries looks like, just like you would expect in a regular table and I have a bunch of these rows, which are entries in this table, same for Track here, I have a top, I have some information here, that gives me just basic information about what each of these columns means and then I have, let me expand that out, so you can see, and then I have rows, which are entries in this table and so this database lingo also uses the same conceptualization of rows and column, so a row would be a slice this way and rows are just entries inside of these tables and then columns represent things, represent slices across all of the rows, so here's a Composer column inside of this column, has all of the different composers for each of the particular pieces of information, so you can kind of conceptually think of a database as being organized in a spreadsheet fashion like this. Now they have lots of advantages over just using spreadsheets that I'll get to in a second, but conceptually you can think of a database as being organized in this fashion, where each of the different sheets here represent different tables, I have one table per sheet, if you wanna think of it in that way and then each table has column rows and columns, just like you would expect a regular table to do, except the thing about databases is that they can handle millions and millions of rows in a very efficient manner and we're gonna see, we're gonna learn and experiment, we don't quite have a million rows, but we'll use something a little over a half a million rows and we'll see what the difference is, if we use a database versus if we use a text file, if we store that in a CSV or a text file like that and you'll see that there's a staggering difference in how long it takes to ask just a very simple question, but we'll get to that kind of towards the end.

And so the thing about, like I was getting back to, databases are great for handling very large amounts of data, better than most of the spreadsheets can and also much better at doing question answering or querying of this data in a very efficient and fast manner, faster than a, they're a bit more efficient than using spreadsheets. So I've been talking a lot about querying and we also have the other purpose of having databases, so we can manage them, but how do we do this? Well, we use a kind of language called Structured Query Language or SQL or S-Q-L and we can use that kind of language to ask questions or query the database as well as to kind of do management things, such as adding new entries, adding new rows into this database, changing rows, getting rid of rows and whatnot and we can use it also to create new tables as well.