Please post the code that gives that error.
I guess you need to rename your sub to dbconnect like shown here. You can't use connect because it is a DBI method.

I have posted the code .Please look into it.

I had to pass like this how can i pass it for the above script which you had included? $site{$site}{'current'} = "a_$site\_current";

use Getopt::Long;
GetOptions("site=s" => \my $site)
    or die "Error in command line arguments\n";
    
defined $site
    or die "usage: $0 site_name\n";

my %site_map = (
   site1 => { host => 'am.d.aog.com', db=>'site1', user=>'db_cad', pw=
+>'Cad123' },
    site2 => { host => 'am.d.aog.com', db=>'site2', user=>'db_cad', pw
+=>'Cad123' },
);

my $dbh = dbconnect($site);
print $dbh;

sub dbconnect {
    my $s = shift;
    die "bad site $s" unless $site_map{$s};
    my $dsn = "DBI:mysql:database=$site_map{$s}{db};host=$site_map{$s}
+{host}";
    my $dbh = DBI->connect($dsn, $site_map{$s}{'current'}{user}, $site
+_map{$s}{'current'}{pw})
        or die "ERROR: can't connect to database server site $s";
    return $dbh;
}
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This is how i tried from your code.
i got the following error
usage: jan/bin/r.cgi site_name

The error is because you have added another level 'current' into the hash here

$site_map{$s}{'current'}{user},$site_map{$s}{'current'}{pw}

Why ?

i had used current because every database name will have current.So i tried to include those things inside it.

But you didn't change the hash to suit like this

#!perl
use strict;

my %site_map = (
  site1 => { host => 'dam.sd.aog.com', 
             db   => 'a_site1_current', 
          current => { user => 'ad', pw => '123' } },
  site2 => { host => 'dam.sd.aog.com', 
             db   => 'a_site2_current',
          current => { user => 'ad', pw => '123' } },
  site3 => { host => 'dam.sd.aog.com', 
             db   => 'a_site3_current',
          current => { user => 'ad', pw => '123' } },
);
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