Can't call method "do" - DBI Troubles

vbrtrmn has asked for the wisdom of the Perl Monks concerning the following question:

Hey, I'm having some probs w/ DBI today. My code bombs with:

Can't call method "do" on an undefined value at /var/www/html/sites/www.auroraborealis.org/cgi-bin/gbdbconnect.cgi line 19.

Here's my code:

#!/usr/bin/perl -w

use strict;
use DBI;
use CGI::Carp "fatalsToBrowser";
use CGI ":all";

my $username = 'USERNAME';
my $pass = 'PASSWORD';

my $db = 'DBI:mysql:auroraborealis:localhost';
my $db_object = DBI->connect($db, $username, $pass);


print header();
print "<PRE>";

my $sql = "SELECT * FROM guestbook ORDER BY name";
my $dbh->do($sql);
$dbh->disconnect();

exit;
[download]

--
paul

Comment on Can't call method "do" - DBI Troubles Download Code

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Re: Can't call method "do" - DBI Troubles by broquaint (Abbot) on Feb 03, 2003 at 14:05 UTC
Change your database assignment line to `my $dbh = DBI->connect($db, $username, $pass);` [download] And the line with `do` on it to `$dbh->do($sql);` [download] You'll also probably want to check the return of both of those statements in case they fail. HTH `_________ broquaint`	[reply] [d/l] [select]
Re: Can't call method "do" - DBI Troubles by robartes (Priest) on Feb 03, 2003 at 14:17 UTC
To expand on broquaint's perfectly correct answer: The reason your code is not working is because you first assign the reference to the DBI object (commonly called the Database handle, hence $dbh) to db_object: `my $db_object = DBI->connect($db, $username, $pass);` [download] after which you try to access it through a new variable $dbh, which is of course undefined: `my $dbh->do($sql);` [download] hence the error. I suspect that you put in the my because the compiler complained about a missing package name on $dbh. You need to drop the my. CU Robartes-	[reply] [d/l] [select]
Re: Can't call method "do" - DBI Troubles by Cabrion (Friar) on Feb 03, 2003 at 14:28 UTC
Adding one more suggestion to this list of correct answers, you should probably trap some errors with . . . `my $dbh = DBI->connect($db, $username, $pass) \|\| die $DBI->errstr();` [download] and `my $dbh->do($sql) \|\| die $dbh->errstr();` [download] to catch any underlying problems with the connection process or underlying SQL execution.	[reply] [d/l] [select]
Re: Re: Can't call method "do" - DBI Troubles by Hero Zzyzzx (Curate) on Feb 03, 2003 at 17:58 UTC
You can use the RaiseError option in the connect() method to automatically "status check" all calls to database functions, a nice little time saver. Note: you still have to status check the connect() method itself. . . `my $dbh=DBI->connect($db,$username,$pass,{RaiseError => 1}) or die("Co +uldn't connect to database ".DBI::errstr);` [download] and the statement `$dbh->do($sql);` [download] will automatically have status checking done for it, as well as any other calls to DBI. -Any sufficiently advanced technology is indistinguishable from doubletalk.	[reply] [d/l] [select]
Re: Can't call method "do" - DBI Troubles by electrosphere (Beadle) on Feb 03, 2003 at 17:14 UTC
Perl is asking you to look hard at line 19... You must run the 'do' on a defined database handle. The database handle is ruturned by the DBI->connect method. In your code this handle is stored in $db_object (I think $dbh would be a better identifier - database Handle). Change line 19 to: `$db_object->do($sql);` I think you want to use the prepare/execute methods when working with SQL Selects as the do method does not return a statement handle (see perldoc DBI for more info)	[reply]