Test dla Electricity Exchange

_zadanie-dla-electricity-echange

// tytuł

package-lock.json

{
  "lockfileVersion": 1,
  "dependencies": {
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}

package.json

{
  "scripts": {
    "start": "node server.js"
  },
  "name": "electricity-exchange-test",
  "version": "1.0",
  "dependencies": {
    "mysql": "^2.14.1"
  }
}

server.js

const mysql = require('mysql');

const connection = mysql.createConnection({
    host     : 'localhost',
    user     : 'maja',
    password : 'pass',
    database : 'db'
});

connection.connect(function(err) {
    if (err) {
        console.error('Error connecting to the database');
        return;
    }

    console.log('Connected to database. Updating every 1s...');
    updateDatabase();
});

function updateDatabase()
{
    connection.query('TRUNCATE TABLE dsu_data', function (error, results, fields) {
        if (error) {
            console.log('Error clearing dsu_data table');
            process.exit(1);
        }
        connection.query('SELECT distinct dsu_id FROM site_data', function (error, dsuIds, fields) {
            if (error){
                console.log('Error reading site_data table');
                process.exit(1);
            }
            let inserts = dsuIds.length;
            dsuIds.forEach(function(dsuId) {
                connection.query('INSERT INTO dsu_data VALUES(?, (SELECT SUM(power) FROM site_data WHERE dsu_id=?))', [dsuId.dsu_id, dsuId.dsu_id], function (error, results, fields) {
                    if (error){
                        console.log('Error insertng data into dsu_data table');
                        process.exit(1);
                    }
                    inserts--;
                    if (inserts == 0)
                        setTimeout(updateDatabase, 1000);
                });
            });
        });
    });
}