Querying Data from Table using Node

In this article, we will see how to select or query the data from a database based on different table fields and columns.

Before proceeding, please check the following steps are already executed −

• mkdir mysql-test

• cd mysql-test

• npm init -y

• npm install mysql

The above steps are for installing the Node - mysql dependecy in the project folder.

Select Data from Table Using Node

• Create a new file with the following name – app.js

• Copy and Paste the following code snippet in this file.

• Now, run the following command to check the output of the above program.

>> node app.js

Example

// Checking the MySQL dependency – if exists
var mysql = require('mysql');

// Creating connection with the mysql database
var con = mysql.createConnection({
   host: "localhost",
   user: "yourusername",
   password: "yourpassword",
   database: "mydb"
});

con.connect(function(err) {
   if (err)
   console.log("Unable to connect to DB ", err);
   con.query("SELECT * FROM students", function (err, result, fields) {
      if (err) throw err;
      console.log(result);
   });
});

Output

It will return all the records present in the students table:
[ RowDataPacket { id: 1, name: 'John', address: 'Delhi'},
RowDataPacket { id: 2, name: 'Pete', address: 'Mumbai'},
RowDataPacket { id: 3, name: 'Amy', address: 'Hyderabad'},
RowDataPacket { id: 4, name: 'Hannah', address: 'Mumbai'},
RowDataPacket { id: 5, name: 'Mike', address: 'Delhi'}]

Querying Data from Table Using Node

The following code snippet gives us an example how we can use SQL queries to query and select data from Node.

Example

// Checking the MySQL dependency – if exists
var mysql = require('mysql');

// Creating connection with the mysql database
var con = mysql.createConnection({
   host: "localhost",
   user: "yourusername",
   password: "yourpassword",
   database: "mydb"
});

con.connect(function(err) {
   if (err)
   console.log("Unable to connect to DB ", err);
   con.query("SELECT * FROM student where address='Delhi'; ", function (err, result, fields) {
      if (err) throw err;
      console.log(result);
   });
});

Output

It will return result based on our filter −

[ RowDataPacket { id: 1, name: 'John', address: 'Delhi'},
RowDataPacket { id: 5, name: 'Mike', address: 'Delhi'}]