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Displaying posts with tag: mysqldb (reset)
MySQLdb Manage Columns

Sometimes trying to keep a post short and to the point raises other questions. Clearly, my Python-MySQL Program post over the weekend did raise a question. They were extending the query example and encountered this error:

      TypeError: range() integer end argument expected, got tuple.

That should be a straight forward error message because of two things. First, the Python built-in range() function manages a range of numbers. Second, the row returned from a cursor is actually a tuple (from relational algebra), and it may contain non-numeric data like strings and dates.

The reader was trying to dynamically navigate the number of columns in a row by using the …

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Python-MySQL Program

This post works through the Python configuration of Fedora instance, and continues the configuration of my LAMP VMware instance. It covers how you add the MySQL-python libraries to the Fedora instance, and provides the students with one more language opportunity for their capstone lab in the database class.

A standard Fedora Linux distribution installs Python 2.7 by default. Unfortunately, the MySQL-python library isn’t installed by default. You can verify the Python version by writing and running the following program before installing the MySQL-python library:

# Import sys library.
import sys
# Print the Python version.
print sys.version

You can run the program dynamically like this from the current working directory:

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Does Python MySQLdb Make You Wait?

Recently while writing a data loading application for a customer, we’ve come into a problematic situation with the Python MySQLdb module that can be installed with base RHEL repository or DVD. As a little background, this application uses an HA architecture where a Virtual IP can be assigned to different servers during a failover scenario. However, during failover, as long as the VIPs are not re-assigned, the application could hang waiting for query response. A quick strace reveals something like:

sendto(5, "W\0\0\0\3SELECT * FROM"..., 91, 0, NULL, 0) = 91

Further test reveals that this problem will not timeout until after about 15 minutes which matches the default tcp_retries2 value on the system (see man 7 tcp):

[root@node1 ~]# cat /proc/sys/net/ipv4/tcp_retries2

It turns out that this version of MySQLdb module has client net read and write timeouts set to 0 allowing the TCP setting …

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kajtajm: Planning my first Python / PyObjC / MySQLdb project

Never have I planned a program so much in detail before starting coding. And stranger still, I’m planning the program to be coded in a language in which I haven’t written a single line of code. Nonetheless, I’m eager and it feels good.

I woke up early this Sunday, my mind concentrating on the many steps I will have to take before the first project will see the light of day. I had planned eight prerequisite lessons before even starting the coding. And despite receiving many good pieces of advice, nobody had relieved me of my main worry — the input grid for the data entry in matrix format.

To speed up things, I thought of writing some auto-generated INSERT statements from the current Google Spreadsheet that I’ve been using. I would then at least have the basic data from the first two weeks of the year to play around with in my MySQL database.

And then it struck me: I don’t need a grid at …

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Python Mysql Connectivity

How do you configure python for use with mysql? You require the MySQLdb module for connecting to mysql server using the python code. This module is used for firing queries to the database server and handling of result sets from python code.

First of all, check if the module is available or not :

jayant@jayantbox:~$ python Python 2.5.2 (r252:60911, Apr 21 2008, 11:17:30) [GCC 4.2.3 (Ubuntu 4.2.3

Showing entries 1 to 5