Skip to main content

Database Study Note: Four Basic MongoDB Commands You Should Know


MongoDB is one of the most popular database with Node.js and Express.js. It is a NoSQL database.

From Google Image
Firstly, we need to install MongoDB in our server. The course TA created a good installation tutorial video on YouTube.

Since the MongoDB has updated its system. In the installation, we need to set up the Ubuntu 16.04 (Xenial) code instead of 14.04 version which is shown on the video.

 Once we finish the installation, we need to call "./mongod" and run the code, then open a new terminal window, and call "mongo", then you are ready to use Mongo shell, which is like JavaScript console. 

We can type "help" to learn the main MongoDB commands and their explanation. 

After I learned this lecture, I summarized four basic MongoDB commands to do with your database: insert, find, update and remove.

Insert

I want to create a student databases which include student name and GPA score. I can use insert command to create the new data: db.students.insert({name: "Mary", GPA: "3.5"}).


In the code, "db" is the database we are on. "Students" is the collection, and "insert" is the command that will insert data into this students collection in the database.

I insert in an object with the student name "Mary" and GPA "3.5". If  I want to see the collection name, I can simple type "show collections". It gives me the "Students".



Find

To prove that the students collection is created, I use "find" to view the data: db.students.find().


Then, you can see the data in students collection with unique Mongo ID.

I insert a new student data, and then use the find command to view all the data.


If I only want to find the student with name equal to "Mary", I can type an object inside the find command: db.students.find({name: "Mary"}). It will give me all the data related to Mary.


Update

 If I want to update an existing student data by change the name "Mike" to "Tom", I could use update command: db.students.update({name: "Mike"}, {$set {name: "Tom"}})


Update takes two different things: the first one is something we select by. In this case, I select the student name "Mike". The second thing is how we want to update. I updated the name to "Tom".

Then, I call find command to see the new data. I can see the new name "Tom" has updated successfully.

Remove

If I want to remove the data, I can use remove command: db.students.remove({name: "Mary"}). Inside the remove, I can put the student name or GPA or ID to remove the data.


Remove will remove everything matches whatever you provide by default.






Labels:

Comments

Post a Comment

Popular posts from this blog

Intermediate Express.js: How To Add Styles & Partials in EJS File?

So far, we only have simple HTML tags and ejs tags in each ejs file. Every template page has no style at all. And the basic HTML header and footer are also missing. Today, I learned how to add styles and partials in ejs file. Link Style Step One: Touch a Separate CSS file I create a new directory "Style" under the "EJSDemo" directory, then I add a new CSS file "app.css" inside "Style" folder. Step Two: Add app.use(express.static()) in the app.js I add app.use(express.static("style")) in the "app.js". This will tell Express.js to serve the content of "Style" directory. Step Three: Write styles in CSS file I simple give body an orange background color and set text color to be grey. Step Four: Link to CSS file in the EJS file I just add <link> tag to link the "app.css" file on the top of the h1 tag in each ejs template. As the result, when I run the app and...
Post a Comment
Read more

Intro to Backend: Is Browser The Only Place To Send HTTP Request?

Today,  I begin to learn the second part of web develop course: backend. Frontend is the stuff that we can see and interactive with, such as HTML, CSS, and JS. We can type our code, style our page, or write some function to make interaction. However, backend is everything else. For example, we type Target web address in the Internet Browser. As we hit "enter", there are a few steps to go through: 1. The HTTP request is sent to a particular server's IP address. 2. The server figures out what to send us 3. It sends a HTTP response back to us Those process we are hard to see, and it happens in less than one second. The instructor said that the browser is not the only place to send the HTTP request, and there are so many choices out there. In this learning course, we are going to use Postman App . Postman allows us to make HTTP requests and viewer responses. It is really for developers to understand how things are working or debug something. In the P...
Post a Comment
Read more

Intermediate CSS: Three Steps To Create A Photo Gallery

I have seen many image blogs these years. People love to post their photos online to express life and feeling.  Image is powerful because it could bring a visual story to audience. People can see what you see, and may be feel the same way as you feel, too. If we want to build our own photo gallery, what should we do? Luckily, the boot-camp instructor just showed me how to use HTML and CSS to create a simple photo gallery.  I would love to share my study note here. (p.s. all the image links are provided by Udemy course instructor) Step One: Add Image Links on HTMLPage The instructor provides all the image links. All we need to do is add those links inside the <img> tag. Without CSS, the page will looks like this: they are not organized, and sizes are different, too. Step Two: Set Image Property Values We set the width of each photo the same value which is 30%, so there will be three images per line. The percentage value can help...
Post a Comment
Read more