var oracledb = require('oracledb');

dbquery = function(user, pass, db, query, callback) {
  oracledb.getConnection({ user : user, password : pass, connectString : db }, function(err, connection) {
    if (err) {
      callback("Couldn't connect to db " + db + " got an error " + err, null);
    }
    connection.execute(query, function(err, result) {
      if (err) {
        callback("Couldn't execute query in db " + db + " got an error " + err, null);
      }
      callback(null, result.rows);
    });
  });
}

dbquery("oracledb", "oraclepass", "localhost:1521/oracledbs", "SELECT * FROM Users", function(err, res) {
  if (err) {
    console.log(err);
  } else {
    console.log(res);
  }
});