Simple python3 script that defines a set of functions to create, populate and query a balance database to keep track of your transactions.

balanceDB.py

#!/usr/bin/env python5

import rlcompleter, readline
readline.parse_and_bind('tab:complete')

import atexit

from calendar import month_abbr
import sys
import math
import sqlite3
import matplotlib.pyplot as pyplot

dbname = sys.argv[1] if len(sys.argv) > 2 else 'balance.db'

conn = sqlite3.connect(dbname)
c = conn.cursor()

def create_db():
  c.execute("""CREATE TABLE transactions (id integer primary key autoincrement,
day int not null, month int not null, year int not null,
credit_units int not null default 0, credit_decimals int not null default 0,
debit_units int not null default 0, debit_decimals int not null default 0,
description nvarchar(255) not null, type int not null default 0)""")
  conn.commit()

"""
Array to be filled in with values
Example:
transactions = [
(1, 1, 2014, 50, 0, 0, 0, "Friend's loan payback")
(31, 12, 2014, 0, 0, 100, 50, "New Year's Eve party!")
]
"""
transactions = []
  
def insert_values(transactions):
  query = """INSERT INTO transactions (day, month, year,
credit_units, credit_decimals, debit_units, debit_decimals, description)
VALUES (?, ?, ?, ?, ?, ?, ?, ?)"""
  c.executemany(query, transactions)

def total_balance():
  c.execute("""SELECT sum(credit_units), sum(credit_decimals),
sum(debit_units), sum(debit_decimals) FROM transactions""")
  ans = c.fetchall()
  ans = ans[0]
  print("Credit: " + str((ans[0]*100 + ans[1])/100))
  print("Debit: " + str((ans[2]*100 + ans[3])/100))
  return (ans[0]*100 + ans[1] - ans[2]*100 - ans[3])/100

def print_transactions(filename="balance.txt"):
  f = open(filename, 'wt')
  c.execute("select * from transactions")
  ans = c.fetchall()
  for row in ans:
    f.write("%4d:\t%02d/%02d/%4d\t%5d.%02d €\t%5d.%02d €\t%s\n" % row[0:9])
  f.close()

def export_db(filename="export.txt"):
  c.execute("pragma table_info(transactions)")
  ans = c.fetchall()
  
  header = ''
  for row in ans:
    header += row[1] + '|'
  header = header[0:90]
  
  f = open(filename, 'wt')
  f.write(header + '\n')
  
  c.execute("select * from transactions")
  ans = c.fetchall()
  for row in ans:
    line = ''
    for i in range(10):
      line += str(row[i]) + '|'
    f.write(line[0:len(line)-1] + '\n')
  f.close()

def import_db(filename):
  create_db()
  f = open(filename, 'r')
  
  header = f.readline()
  header = header[0:len(header)-1].replace('|', ', ')
  
  ans = f.readlines()
  transactions = ''
  for row in ans:
    transactions += '(' + row[0:len(row)-1].replace('|', ', ') + '), '
  transactions = transactions[0:len(transactions)-1]
  
  c.execute("INSERT INTO transactions (%s) VALUES %s" % (header, transactions))
  conn.commit()

def monthly_graph():
  c.execute("""SELECT month, year, sum(credit_units), sum(credit_decimals),
sum(debit_units), sum(debit_decimals) FROM transactions GROUP BY year, month""")
  ans = c.fetchall()
  
  xmax = len(ans)
  xcred = [x - 0.4 for x in range(1,xmax+1)]
  ycred = [row[2]+row[3]/100 for row in ans]
  xdebt = [x + 0.4 for x in xcred]
  ydebt = [row[4]+row[5]/100 for row in ans]
  #ymax = math.ceil(max(ycred + ydebt))
  ymax = 2500;
  
  pyplot.figure(num=None, figsize=(30, 14.0625))
  pyplot.axis([0, xmax+1, 0, ymax])
  pyplot.yticks([i*100 for i in range(0, math.ceil(ymax/100)+1)])
  pyplot.xticks(range(1, xmax+1), [month_abbr[row[0]] + " " + str(row[1]) for row in ans],\
rotation=25, ha='right')
  pyplot.grid(b=True, axis='y', zorder=1)
  pyplot.bar(xcred, ycred, width=0.4, color='green', label='Credit', zorder=5)
  pyplot.bar(xdebt, ydebt, width=0.4, color='red', label='Debit', zorder=5)
  pyplot.legend()
  pyplot.title('Balance')
  pyplot.savefig('graph.png')

@atexit.register
def close():
  print("Closing database...")
  conn.close()