Solved

Using Perl and MySQL

Posted on 2002-06-03
7
259 Views
Last Modified: 2010-03-05
I have written Perl code to access a MySQL database.  I am changing the code to cache previously loaded web pages into a 4k text buffer in the database.  The internet response is loaded into a variable called $response as follows:
  $req=HTTP::Request->new("GET", $url);
  $req->content_type('application/x-www-form-urlencoded');
  $response=$ua->simple_request($req);

To save the information the following is done:
  $respstr = $response->as_string;
  $respstr1 = substr($respstr, 0, 4000);
  $cachepage = $respstr1;
  $sql = "update links set cachepage='$cachepage' where id=$id";
  $tda = $dbh->prepare($sql) or die "Error preparing: ", $dbh->errstr;
  $tda->execute or die "Error executing: ", $dbh->errstr;

The variable $cachepage is a text type in the MySQL database.  

When the execute is attempted, no response is returned and I am sure it fails since the database is not written to.
Do I need to set a length work or something to get this to work?  Thanks for any help.
0
Comment
Question by:mzehner
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 2
  • 2
7 Comments
 
LVL 1

Expert Comment

by:bluprint
ID: 7051898
$tda->execute or die "Error executing: ", $dbh->errstr;
$dbh->commit; ## <- you need to commit the update.
0
 
LVL 2

Author Comment

by:mzehner
ID: 7052391
It still does not work even with $dbh->commit;.  There is no error message, but unless the line:
$tda->execute or die "Error executing: ", $dbh->errstr;
is commented out the web page will not return output.
0
 
LVL 1

Expert Comment

by:bluprint
ID: 7052444
Silly question...but are you connecting to the DB first?

You also should escape the single quotes

$sql = "update links set cachepage=\'$cachepage\' where id=$id";

I'm pretty sure this is the case...I did a project with MySQL once so this is from memory, also I don't have immediate access to some tools such as perl... In any case, it won't hurt....

One other thing, you shouldn't need to prepare that update statement. Just do:

$sql = "update links set cachepage=\'$cachepage\' where id=$id";
$dbh->do($sql);
if($DBI::err != 0) {
  print "error here!\n";
  print $dbh->errstr;
}
$dbh->commit;

Maybe something in there will move you in the right direction...
0
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 4

Expert Comment

by:dda
ID: 7053203
Also add this to your script:

use CGI::Carp qw(fatalsToBrowser);

It will cause 'die' messages to go to your browser.
0
 
LVL 2

Author Comment

by:mzehner
ID: 7058046
bluprint:
I am connecting to the database first since I am performing successful queries prior to the code I posted above.

dda:
I tried your suggestion.  It worked with an interesting error.  I stated that I have an error in my SQL syntax near 'Gave information here'.
The interesting thing about the information is that it is part of the string that I am writing to the database.  This is why I suspect that it is a possible problem with the syntax of the variable being written.  I have not used blob or text types (beyond 255 characters) with MySQL before.

I removed:
$respstr = $response->as_string;
and the program worked responded with the text output I placed at the end of it.  It appeared to work, but I'm not sure the datbase contains the web page contents.

Therefore part of the problem was that I was converting it to a string before saving to the database.  I'm not sure why this caused a problem.  I still need to investigate to tell if the data was wriiten to the database.  It does not appear in MySQL admin.
0
 
LVL 4

Accepted Solution

by:
dda earned 100 total points
ID: 7058750
I bet you have single or souble quotes in yout text being inserted into database. You can mask them with '\' or, better way, use placeholders and parameters to execute():

$sql = "update links set cachepage=? where id=?";
$tda = $dbh->prepare($sql) or die "Error preparing: ", $dbh->errstr;
$tda->execute($cachepage, $id) or die "Error executing: ", $dbh->errstr;
0
 
LVL 2

Author Comment

by:mzehner
ID: 7065892
Thanks, your comments helped me debug and solve the problem.
0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Perl strange behaviour 5 74
How to strip .csv from file name 9 84
To run CGI/perl on tomcat and connect to oracle database. 5 146
Regex rule to match two different url 5 76
On Microsoft Windows, if  when you click or type the name of a .pl file, you get an error "is not recognized as an internal or external command, operable program or batch file", then this means you do not have the .pl file extension associated with …
Checking the Alert Log in AWS RDS Oracle can be a pain through their user interface.  I made a script to download the Alert Log, look for errors, and email me the trace files.  In this article I'll describe what I did and share my script.
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…

726 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question