Newbie needing some help
Mark Lawrence
breamoreboy at yahoo.co.uk
Fri Aug 8 17:54:27 EDT 2014
On 08/08/2014 20:07, Matt Smith wrote:
> I am trying to write a program that will loop through a text file and
> delete rows in a mysql database.
>
> It seemingly runs but I don't see anything getting deleted in the db.
> Is there anything apparent that I am missing?
>
> This is the code:
> #!/usr/bin/python
> import mysql.connector
> #
> f=open('/home/smithm/email-list.txt', 'r')
The modern idiom is:-
with open(...) as f: but that doesn't matter here.
> for line in f:
> #<do something with line>
> # Open database connection
> db = mysql.connector.connect(user="xx", password="xx",
> host="localhost", database="xx")
>
> # prepare a cursor object using cursor() method
> cursor = db.cursor()
Are you aware that you're connecting to your db and setting up the
cursor in every iteration of the loop?
>
> # Prepare SQL query to DELETE required records
> sql = "DELETE FROM tblc_users WHERE user_email=%s, % (line)"
> try:
> # Execute the SQL command
> cursor.execute(sql)
> # Commit your changes in the database
> db.commit()
> except:
This bare except is masking every possible thing that can go wrong.
Strip it out and I expect you'll find your mistake in seconds. Once
you've corrected your code add back in the bare minimum number of
exceptions that you really should catch.
> # Rollback in case there is any error
> db.rollback()
>
> # disconnect from server
> db.close()
>
> --
> Matthew Smith
>
--
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.
Mark Lawrence
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