var db_config = {
    host: 'localhost',
    user: 'root',
    password: '',
    database: 'db',
};

var connection;

function update_query(param1) {
    return new Promise(function (resolve, reject) {
        try {
            connection = mysql.createConnection(db_config);
            connection.connect(function(err) {
                if(err) {
                    console.log('error when connecting to db:', err);
                }
            });


            var query_str =
                    //SQL statement. Blah blah
                    "UPDATE XXX " +
                    "SET YYY=?"
                ;
            var query_var=param1;
            connection.query(query_str, query_var, function (err, rows, fields) {
                if (err) {
                    console.log(err);
                    logger.info(err);
                    return reject(err);
                }
                else {
                    resolve(rows);
                }
            });
        } catch (err) {
            reject(err);
        }
    });
}