modifying html input date for mysql, reg ex or string interpolation?

[Kun]

I have an html form that takes dates and inserts them into a mysql file. 
  Currently, users have to type in dates in the yyyy-mm-dd format.  As 
of now, this process works with the sql.  However, I would like to make 
this process easier by:

1) providing drop down menus for year, month, and date respectively.


in a failed attempt, i tried made 3 drop down lists (dateyear, 
datemonth, dateday) respectively and then used string interpolation to 
tie them together into a yyyy-mm-dd string called 'date'.  I then tried 
to use this 'date' string in my original sql query and it no longer worked.

Is this because the new 'date' value is a string instead of an int?  How 
can I go about solving this problem and making the new 'date' string 
work with my old sql query?


Attached is my code:


#!/usr/bin/env python

import cgi
print "Content-type: text/html"
print

form = cgi.FieldStorage()
print form.keys()


#gets value for each input
price = form["price"]
price = price.value
purchasetype = form["purchasetype"]
purchasetype = purchasetype.value
date = form["date"]
date = date.value
comment = form["comment"]
comment = comment.value


dateyear = form["dateyear"]
dateyear = dateyear.value
datemonth = form["datemonth"]
datemonth = datemonth.value
dateday = form["dateday"]
dateday = dateday.value


#string interpolation for date
date = "%d-%d-%d" % (dateyear, datemonth, dateday)
print "<br>"



for x in form.keys():
    print "%s=%s" % (x, form[x].value) + "<br>"


# make connection to MySQL
import MySQLdb
import re
import urllib
import sys

try:
	connection = MySQLdb.connect(host="localhost", user="xxxx", 
passwd="xxxx", db ="xxxx")

except MySQLdb.Error, e:
	print "Error %d: %s" % (e.args[0], e.args[1])
	sys.exit (1)

#take data and put it into table that you have created.
cursor = connection.cursor()
mysqlstatement = ""
mysqlstatement = "INSERT INTO dir (date, purchasetype, price, comment) 
VALUES ('"+ date +"','"+ purchasetype +"','"+ price +"','"+ comment +"' )"
print mysqlstatement
cursor.execute (mysqlstatement)