db.commit() to take effect

[John Machin]

progman wrote:
> I was testing the python+mysql
>
> here are my sample codes:
> ------------------------
> import MySQLdb
> from pprint import pprint
> db = MySQLdb.connect(host="localhost", user="root", passwd="password",
> db="database")
> cursor = db.cursor()
> cursor.execute('update promo set date=100")
>
>
> ------------------------
>
> i was expecting the cursor.execute will update my db immediately.
> it wasn't. not until i  run db.commit(), then only i see the value
> changes.
>
> it that the right way to update db?

Short answer: yes

Longer answer: In most non-trivial db apps, to carry out a given
real-world transaction, you will need to do multiple updates/inserts,
and you want them all to happen, or none to happen. The database would
be inconsistent if your app or server crashed half-way through. Imagine
you are transferring some money to someone else's bank account. The
money gets deducted from your account but not added to theirs -- not
good. [A real banking system would not be that simple, but you should
get the general idea.]  So you do db.commit() after the last
insert/update.

HTH,
John