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  RE: using mysql NULL with IF statement         


Author: T Baetzler
Date: Jul 13, 2008 23:56

Huub gmail.com> asked:
> I'm adapting a Perl script using MySQL connectivity, and have
> to compare a variable, e.g. $myvar, with the value NULL from
> the database. In MySQL, I have to use the query 'where myvar
> is null', which works great.
> But when I try this in Perl, like 'if ($myvar == null)' or
> 'if ($myvar is null)' it ends in error. I read the DBI FAQ on
> this, but didn't find an example of IF and NULL. Can somebody
> tell me how I can or should do this?

See the DBI manpage, Subsection "Notation and Conventions":
"NULL values are represented by undefined values in Perl".

You check that by using statements like

if( defined( $myvar ) )

HTH,
Thomas
no comments
  question about "local our"         


Author: Roman Makurin
Date: Jul 13, 2008 20:17

Hi All!

I want to ask whats difference between usage of "local" and "local our"

Here is example code:

#!/usr/bin/perl

use strict;
use warnings;

our $i = 0;

sub t_func1 {
local $i = 1;
print "\$i = $i\n";
}

sub t_func2 {
local our $i = 2;
print "\$i = $i\n";
}

t_func1();
t_func2();
print "\$i = $i\n";
Show full article (0.45Kb)
2 Comments
  using mysql NULL with IF statement         


Author: Huub
Date: Jul 13, 2008 12:54

Hi,

I'm adapting a Perl script using MySQL connectivity, and have to compare
a variable, e.g. $myvar, with the value NULL from the database. In
MySQL, I have to use the query 'where myvar is null', which works great.
But when I try this in Perl, like 'if ($myvar == null)' or 'if ($myvar
is null)' it ends in error. I read the DBI FAQ on this, but didn't find
an example of IF and NULL. Can somebody tell me how I can or should do this?

Thanks.
2 Comments