How to save connection result in a variable in Node.js ?

Last Updated : 7 Apr, 2021

We are going to use the query function in MySQL library in node.js that will return our output as expected. Using this approach, we can save connection result in a variable in Node.js.

Setting up environment and Execution:

Step 1: Initialize node project using the following command.

npm init

Step 2: Turn on MySQL Database

Step 3: After creating the NodeJS application, Install the mysql module using the following command.

npm install mysql

Database Table: Our sample gfg_table database with look like this.

Step 4: Create an index.js file with the following code.

index.js 
const mysql = require("mysql");

var db_con = mysql.createConnection({
    host: "localhost",
    user: "root",
    password: "",
    database: "gfg_db"
});

let output;

const setOutput = (rows) => {
    output = rows;
    console.log(output);
}

db_con.connect(async(err) => {
    if (err) {
        console.log("Database Connection Failed !!!", err);
        return;
    }

    console.log("Connected to Database");

    let query = 'SELECT * FROM users';
    db_con.query(query, (err, rows) => {
        if (err) {
            console.log("internal error", err);
            return;
        }
        
        // This is the important function
        setOutput(rows);
    });
});

Step 5: Run the index.js file using the following command.

node index.js

Output:

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