The formatting of that last "default" line makes it harder than it should be. This solution relies on the amount of whitespace at the start of column definitions.

#!/usr/bin/perl

use strict;
use warnings;

my $tab;
while (<DATA>) {
  if (/create table.+\.(\w+)/) {
    $tab = $1;
  }

  if (/^    (\w+)/) {
    print "$tab.$1\n";
  }
}

__DATA__
create table "metrica".vodafone_capacity_cell_count_week
  (
    nc_id integer,
    cell_id varchar(50) not null ,
    week_of integer not null ,
    busy_hour "informix".utime,
    gsm_tch_cong_pc_range_1 integer,
    gsm_tch_cong_pc_range_2 integer,
    gsm_tch_cong_pc_range_3 integer,
    gsm_sdcch_cong_pc_range_1 integer,
    gsm_sdcch_cong_pc_range_2 integer,
    gsm_sdcch_cong_pc_range_3 integer,
    gsm_sdcch_cong_pc_range_4 integer,
    gsm_hr_tch_util_pc_range_1 integer,
    gsm_hr_tch_util_pc_range_2 integer,
    gsm_hr_tch_util_pc_range_3 integer,
    gsm_hr_tch_util_pc_range_4 integer,
    gsm_hr_tch_util_pc_range_5 integer,
    gprs_cong_pc_range_1 integer,
    gprs_cong_pc_range_2 integer,
    gprs_cong_pc_range_3 integer,
    config_tch integer,
    config_fpdch integer,
    config_trx integer,
    config_layer integer,
    cell_type varchar(25)
        default null
  );
[download]

Have you looked at SQL::Statement? It can parse many types of SQL statements and then return information about these statements. You sound as if you don't have any control over the format that your CREATE statement is sent to you, so parsing with regular expressions without prior knowledge of the formatting will be guesswork. If SQL::Statement works for you, use it instead.

This seems to produce the desired output regardless of how the input is formatted.

#! perl -slw
use strict;

$/ = ';';
while( <DATA> ) {
    m[
        create\s+table\s+
        (?:"[^"]+"\.)* #"
        ( \S+ ) \s*
        \( \s*
          ( .+ )
        \s* \)
    ]smx or warn "*** No match '$_'" and next;

    print "$1.$_" for map{ m[(\S+)] and $1 } split ',\s*', $2;
    print "\n------\n";
}

__DATA__
create table "metrica".vodafone_capacity_cell_count_week
( nc_id integer, cell_id varchar(50) not null , week_of integer not nu
+ll , busy_hour "informix".utime, gsm_tch_cong_pc_range_1 integer,
    gsm_tch_cong_pc_range_2 integer, gsm_tch_cong_pc_range_3 integer, 
+gsm_sdcch_cong_pc_range_1 integer, gsm_sdcch_cong_pc_range_2 integer,
    gsm_sdcch_cong_pc_range_3 integer, gsm_sdcch_cong_pc_range_4
    integer, gsm_hr_tch_util_pc_range_1 integer,

    gsm_hr_tch_util_pc_range_2 integer, gsm_hr_tch_util_pc_range_3 int
+eger, gsm_hr_tch_util_pc_range_4 integer,
    gsm_hr_tch_util_pc_range_5 integer,


    gprs_cong_pc_range_1 integer, gprs_cong_pc_range_2 integer, gprs_c
+ong_pc_range_3 integer,
    config_tch integer, config_fpdch integer, config_trx integer,
    config_layer integer, cell_type varchar(25) default null );
[download]

Produces

vodafone_capacity_cell_count_week.nc_id
vodafone_capacity_cell_count_week.cell_id
vodafone_capacity_cell_count_week.week_of
vodafone_capacity_cell_count_week.busy_hour
vodafone_capacity_cell_count_week.gsm_tch_cong_pc_range_1
vodafone_capacity_cell_count_week.gsm_tch_cong_pc_range_2
vodafone_capacity_cell_count_week.gsm_tch_cong_pc_range_3
vodafone_capacity_cell_count_week.gsm_sdcch_cong_pc_range_1
vodafone_capacity_cell_count_week.gsm_sdcch_cong_pc_range_2
vodafone_capacity_cell_count_week.gsm_sdcch_cong_pc_range_3
vodafone_capacity_cell_count_week.gsm_sdcch_cong_pc_range_4
vodafone_capacity_cell_count_week.gsm_hr_tch_util_pc_range_1
vodafone_capacity_cell_count_week.gsm_hr_tch_util_pc_range_2
vodafone_capacity_cell_count_week.gsm_hr_tch_util_pc_range_3
vodafone_capacity_cell_count_week.gsm_hr_tch_util_pc_range_4
vodafone_capacity_cell_count_week.gsm_hr_tch_util_pc_range_5
vodafone_capacity_cell_count_week.gprs_cong_pc_range_1
vodafone_capacity_cell_count_week.gprs_cong_pc_range_2
vodafone_capacity_cell_count_week.gprs_cong_pc_range_3
vodafone_capacity_cell_count_week.config_tch
vodafone_capacity_cell_count_week.config_fpdch
vodafone_capacity_cell_count_week.config_trx
vodafone_capacity_cell_count_week.config_layer
vodafone_capacity_cell_count_week.cell_type

------

*** No match '
' at c:\test\junk3.pl line 6, <DATA> chunk 3.
[download]

Why use a regex? It'd be better to use a real parser, and I'm probbably going to fail on selecting the fields, but once you get that, just split the list on commas, and choose the first word from each:

local $/ = undef;
my $create_sql = <DATA>;

my ($tablename, $fields) = ($create_sql =~ m/create table ".+?"[.](\w+
+)\s+\((.*?)\);/s);
print "$tablename\n";

foreach my $fieldinfo (split /,/, $fields) {
  my ($fieldname) = ( $fieldinfo =~ m/^\s*(\w+)/ );
  print "$tablename.$fieldname\n";
}

__DATA__
create table "metrica".vodafone_capacity_cell_count_week
  (
    nc_id integer,
    cell_id varchar(50) not null ,
    week_of integer not null ,
    busy_hour "informix".utime,
    gsm_tch_cong_pc_range_1 integer,
    gsm_tch_cong_pc_range_2 integer,
    gsm_tch_cong_pc_range_3 integer,
    gsm_sdcch_cong_pc_range_1 integer,
    gsm_sdcch_cong_pc_range_2 integer,
    gsm_sdcch_cong_pc_range_3 integer,
    gsm_sdcch_cong_pc_range_4 integer,
    gsm_hr_tch_util_pc_range_1 integer,
    gsm_hr_tch_util_pc_range_2 integer,
    gsm_hr_tch_util_pc_range_3 integer,
    gsm_hr_tch_util_pc_range_4 integer,
    gsm_hr_tch_util_pc_range_5 integer,
    gprs_cong_pc_range_1 integer,
    gprs_cong_pc_range_2 integer,
    gprs_cong_pc_range_3 integer,
    config_tch integer,
    config_fpdch integer,
    config_trx integer,
    config_layer integer,
    cell_type varchar(25)
        default null
  );
[download]