python - How to give multiple values to a single key using a dictionary?

Question

I have a html form which has Firstname, LastName, Age and Gender and a ADD button. I enter the data into the form and that gets into the Berkeelys db. What my code does is it prints only the last values. I want that it should show all the values related to particular key

#!/usr/bin/python

import bsddb
import cgi

form = cgi.FieldStorage()

print "Content-type:text/html
"
Fname = form.getvalue('firstname', '')
Lname = form.getvalue('lastname', '')
Age = form.getvalue('age', 0)
Gender = form.getvalue('gender', '')

#print Fname, Lname, Age 

db = bsddb.hashopen("/home/neeraj/public_html/database/mydb.db","w")
db['FirstName'] = Fname  
db['LastName'] = Lname
db['Age'] = Age 
db['Gender'] = Gender
db.close()
db = bsddb.hashopen("/home/neeraj/public_html/database/mydb.db","r")
#db = bsddb.hashopen("/home/neeraj/public_html/database/mydb.db")
print db['FirstName'], db['LastName'], db['Age'], db['Gender']
db.close()
print db 

Answer 1

You should use an SQL database instead of the dict-based interface, since SQL databases already handle multiple tuples in a table.

Anyway, if you want to have a dict interface you can use the shelve module (bsddb is deprecated, so you should avoid it) and save each value in a list:

import shelve

COLUMNS = ('FirstName', 'LastName', 'Age', 'Sex')

the_db = shelve.open('test.db', writeback=True)
for col_name in COLUMNS:
    if col_name not in the_db:
        the_db[col_name] = []

records = [
    ('John', 'Deer', 20, 'M'),
    ('Ada', 'Lovelace', 23, 'F'),
]

for record in records:
    for col_name, value in zip(COLUMNS, record):
        the_db[col_name].append(value)

the_db.close()

the_db = shelve.open('test.db')

for record in zip(*(the_db[col_name] for col_name in COLUMNS)):
    print(record)

the_db.close()

The above code outputs:

('John', 'Deer', 20, 'M')       
('Ada', 'Lovelace', 23, 'F')

---

If you want to use an SQL database you could use the sqlite3 module. For example:

import sqlite3

conn = sqlite3.connect('test.sqlite')

cursor = conn.cursor()

cursor.execute('''
CREATE TABLE people (
    FirstName text,
    LastName text,
    Age int,
    Sex text
    )''')

cursor.execute('''
INSERT INTO people values ('John', 'Deer', 20, 'M')''')

cursor.execute('''
INSERT INTO people values ('Ada', 'Lovelace', 23, 'F')''')

conn.commit()

for record in cursor.execute('''SELECT * FROM people'''):
    print(record)

The above code outputs:

(u'John', u'Deer', 20, u'M')
(u'Ada', u'Lovelace', 23, u'F')

(Note the u'...' simply means that the strings are unicode, it doesn't change their value)

However this code has some problems (e.g. try to run it twice...), but if you want to follow this path then you must learn SQL first, so go ahead and stufy it (there are a lot of online tutorials. For example w3schools ones).