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Node.js : Brief Introduction & How to retrieve data from database

 

Question: You're looking for manufacturing company suppliers in a database. Supplier identification numbers are stored in the supplier_id column. What is the proper clause to retrieve only information about the supplier with the ID number 85317?

See the Answer


Why are the Mongodb, Mariadb, and other databases used?

You are aware that we must save our data; for example, if you own a retail store, you are aware that you must gather various data from customers and keep a record of each customer's billing. This also makes it easier to keep track of sales over time. You may also need to examine data in order to improve your business. We used to write it down with a pen and paper back in the day. However, in today's shopping malls and other types of stores, we use excel sheets to keep track of sales, customer information, and so on. One thing remains constant from the old days and now, when data is being collected. For our businesses, we're putting together a database. In the past, we kept data on computers. However, however, we can simply take data from websites and have the data automatically captured by a database. When you go to a shopping site, for example, you enter your delivery address, quantity of goods, and billing information, and everything is saved in a database. And the administration retrieves data from such databases on a regular basis for a variety of purposes, including improving corporate operations.


Why SQL?

MySQL is a database management system. MySQL was nearly universally used for databases just a few years ago. It's still a demanding server-side scripting language to master. "Server side" refers to the necessity for a server to operate it or for background processing. Any browser that receives the name of a domain, such as 'example.com,' sends a request to the DNS server to retrieve the IP address of that domain/website. The request is then forwarded to the webserver. The HTML webpages are then sent to our browser by the webserver. 

However, whenever we need to process something on the server side, for example, we fill out a form, which puts the data in a database rather than a webserver. If we need to retrieve data from databases as administrators, we send a request to the database, which processes things in the background before sending the relevant data to the client's computer screen.


Clauses that are used to retrieve data from a SQL database

We may link the webserver to the database server using PHP or the Node.js framework, as you know. Without further ado, we'll discuss what clauses are used to retrieve data from MySQL databases

In a database, we primarily perform four types of operations: create/post, edit/update, delete, and, last but not least, get data.


Using node.js to connect a database to a web server (acts as app server)

 Although, you can use PHP too, to create, retrieve, update and delete data from a database.


How to install node.js in your local machine

Go to the URL ‘ n o d e j s . o r g ‘.  Then, depending on your machine, download the appropriate version. Install it when you've downloaded it. Because the 'mysql' module is required to work with databases in node.js, open a command prompt, type the command, and then hit 'enter.'

npm  install mysql 

Then, at command prompt, type 'cd' followed by the folder where you saved the node.js file to launch any node.js code.

After that, type the command line.

node sample.js

Then press the enter key. The name of the node.js file is referred to as'sample.js'.

Note: Because node.js runs on the server, you must first install a local server such as XAMPP or WAMPP before running MySQL queries on your local system; otherwise, it will fail. If you're using 'XAMPP,' launch the programme and start 'MySQL' and 'apache'.


Look at the above page in compatible mode>>


Quiz

In a database, you're looking for manufacturing company suppliers. The supplier id column stores supplier identification numbers. What clause should I use to get only information about the supplier with the ID number 85317?

Answer: use the clause

SELECT * FROM suppliers WHERE suppier_id = '85317'

In the example above, we'll suppose that'suppliers' is the name of a database's table. And the table has other columns, including one called 'suppler_id.'





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