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Hey there! Things are about to get crazy because it’s time to learn all about databases.
We already have a data source that makes our application dynamic. It reads and displays pet data, which happens to be stored in a file called pets.json. If we change something in this file, the site updates automatically. In a fully-built site, you’ll need to read and write lots of data - like a user’s profile, comments, purchases, or maybe forum posts so people can complain about movies. And yea, we could build that site by entirely reading data from flat files - like users.json and angry_movie_forum_posts.json.
A database is a place to put data, just like these files. But instead we store things in tables. And we won’t be using file_get_contents and file_put_contents to read and write data, we’ll use “queries”, which are kind of like human sentences that describe the data you want.
Yea, but what is this database thing? So first, a database is a piece of software you run on your computer, just like a web server like Apache. People can talk to the web server by making requests to our machine, usually to port 80. Actually, in our tutorial, we’ve been using port 8000. A port is like a door and your web server is watching for requests to port 80 so it can process it and return a page.
To talk to a database, we send a “query” to our computer, usually to port 3306. If the database software is running, it watches for queries coming to this door, interprets them, then sends back the data we’re asking for. Yes, we are going to actually do this. But let’s focus on the fact that a database is just a standalone piece of software that we talk with to get data.
To make requests to a web server, we typically use a browser. To send a query to a database, we have a few options. But the most basic is to use a command line program called mysql. MySQL is the most common database software and was installed for you when you installed XAMPP in episode 1.
Let’s open up the command line. In Mac, I can just type “Terminal” into Spotlight to find it. Oh, and “command line” and terminal mean exactly the same thing. If you’re using Windows, we used a terminal inside XAMPP’s control panel in episode 1. I recommend using that or downloading Git, which comes with a nice “Git Bash” terminal program. Windows does have a built-in terminal called “cmd”, but it’s really light on features.
If you are getting a connection error, make sure that MySQL server is running in XAMPP control panel!
We’re going to ease into using the command line, so don’t worry. You probably can avoid using the terminal, but you’ll be a much better developer if you and terminal become friendly.
Ready? Type mysql --help. Bah! MySQL’s help information is a bit chatty. But hey, things are working!
If you get a “command not found” error, make sure that MySQL is installed. If you’re using Windows, try using the XAMPP control panel or Git Bash. A lot of things can go wrong during installation, so do your best to search around for a solution for your operating system.
This mysql program is like a browser to the database. No, it’s not the database, just like your browser is not the website. It just helps us talk to the database, which might live on some other server.
If we give it the IP address to the server where the database software is running, it’ll let us write queries and send those to it. Instead of typing this all into an address bar, we do it like this:
mysql -h localhost --port=3306 -u root -p
This says “I want to talk to a database located at the IP address localhost and go through port 3306. You should log into that database using the user root and you should ask me what the password is.”
When we hit enter, it asks us for a password. XAMPP gives the root user a blank password, so just hit enter. If that doesn’t work, try “root”. We’re in!
Our login information was just sent to “localhost”, which is that special word that points right back to our own machine. It knocked on port 3306. Since XAMPP installed the MySQL database software and configured it to look on this port, MySQL received our details, checked the username and password and basically said, “Welcome, come on in”.
Now for Queries!