Multiple plots against Date and Time using MatPlotLib and Sql3 - python-3.x

Question

This may have been asked before but I have been unable to find it.
I am a newbie to programming and working on a project to actively monitor and record voltage levels of four devices. These details are stored in a sqlite3 db with the date and time they were taken.
I am now trying to create a plot in Matplotlib with all four traces on the same graph, by using the Sqllite3 data. I have got one working although it is a little messy.
Here is my code so far:
import sqlite3
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
from dateutil import parser
import time
import datetime
conn = sqlite3.connect ('Test.db')
c = conn.cursor()
def graph_data():
c.execute('SELECT DTG, Battery_Level1, Battery_Level2, Battery_Leve3, Battery_Level4 FROM Voltages')
data = c.fetchall()
dates = []
values = []
plt.xlabel('Time')
plt.ylabel('Voltage')
plt.title('PiPower Manager')
for row in data:
dates.append(parser.parse(row[0]))
values.append(row[1])
plt.plot_date(dates, values,'-',)
plt.show()
graph_data()
c.close
conn.close()
However I try to add the other lines it appears to cause an error. Any help would be appreciated.
Update 1
I have mostly tried playing with the section
for row in data:
dates.append(parser.parse(row[0]))
values.append(row[1])
I have added a new section similar as below
for row in data:
dates.append(parser.parse(row[0]))
values.append(row[2])
This does graph but looks odd - If I hash out the original it plots ok.
I have then tried adding row[3] and row [4] but I get an error;
Traceback (most recent call last):
File "/home/pi/plot.py", line 41, in <module>
graph_data()
File "/home/pi/plot.py", line 28, in graph_data
values.append(row[3])
IndexError: tuple index out of range
I am not really sure how to go about this......