#!/usr/bin/perl
use strict;
use warnings;
use DBI;
use Data::Dumper;

# Warning, untested as I don have ODBC on this laptop

# I use $dbc to make the line wrap nicer on the monks ;)
my $dbc ='dbi:ODBC:DSN=SqlExpress;UID=USER;PWD=pass;Regional=No;';  
my $dbh = DBI->connect($dbc) or die "Can't connect: $!";

$dbh->{'LongReadLen'} = 40000;
 
# I took out crcp_cod_grupo from the select as its already known in the WHERE
my $sql = ' SELECT crcp_cod_prato';
   $sql.= ' FROM REST.dbo.CRCP_PRATO ';
   $sql.= ' WHERE crcp_cod_grupo = "?"'; # ? is placeholder for bind variable
my $sth = $dbh->prepare($sql);

# lets look at a few different grupos, this is where the
# bin variable gets used. This is more efficient than doing a
# prepare, execute for each grupo.
for my $crcp_cod_grupo (qw(A B C D E)) {
    $sth->execute($crcp_cod_grupo);
    while (my @row = $sth->fetchrow_array) {
       print "Grupo: $crcp_cod_grupo  Prato: $row[0]\n";
    }
}
# I leave the hash version as an excercise for the OP.

$dbh->disconnect;