Updating and creating new elements in a hash table

Question

After i parse a large .sql file this is the printed output from a %hashtable:

Key:AS_LINR 

Value:
Name:DS_LSNE_DDD_TS_A

Type:view




Parents:DM_LINE_END MINA_TI_GRP_V

This is the %hash :

 $hashtable{$name}="Name:$name

Type:$type




Parents:@parents"."\n\n




".


"----------------------------"
;

I need to check each parent if he exists as a key in the %hash . If he does i need to update it and add a new filed named children: , i will add as a value to the field children the name where i first found the parent .Like in this example :

Key:DM_LINE_END 

Value:
Name:DS_LSNE_DDD_TS_A

Type:view
Children:AS_LINR

And i need to do this for each Parent . I want to update a hash by adding new elements to it , and if the key of the has does not exist i have to create one . If i must explain better what i have to do please ask it in comments .

Here is my perl code :

my $var=0;
my @joinparents=();

use warnings;

my %hashtable;
open(DATA,'<','NaViews.sql') or die "Error $!";
open(Writer,'>','ResultFile.txt') or die "Error $!";
open(Writer1,'>','AuxResult.txt') or die "Error $!";

my @create_cmds = ();
my $create_cmd = "";
READ_DATA : while (<DATA>) {
    chop;
    my $ln = $_;

    $ln =~ s/^\s+//;
    $ln =~ s/\s+$//;
    next READ_DATA if($ln =~ /^\-\-/);
    next READ_DATA if($ln =~ /^REM/);

    if($create_cmd ne "") {
        $create_cmd = $create_cmd." ".$ln;
    }

    if($ln =~ /^create/i) {
        $create_cmd = $ln;
    }
    elsif($ln =~ /\;$/) {
        push @create_cmds, $create_cmd;
        $create_cmd = "";
    }
}

close DATA;

my @views = ();

foreach my $create_cmd (@create_cmds) {
    $create_cmd =~ s/\s+/ /;
    $create_cmd =~ s/^\s+//;
    $create_cmd =~ s/\s+$//;
    my $name = get_view($create_cmd);

    my $type = get_type($create_cmd);
    my $content = substr($create_cmd, 0, -1);
    my @parents =();#get_parents();
    my @children = ();#get_children();

#------------------------------------------------------------------------
    my @froms = split(/ from\s+/i, $create_cmd);
    my @joins = split(/ join /i, $create_cmd);

    #parcurge mai multe for in aceeasi structura
    #FOR FROM

        # body...

    foreach my $i (1..@froms-1) {
        #print Writer1 "$froms[$i]"."\n\n";

        my $from = (split(/ where |select | left |  left | right | as /i, $froms[$i])) [0];
        $from=~s/^\s+//;
        $from=~s/\(+//;


        my @Spaces = split(/, | , /,$from);
            foreach my $x (0..@Spaces-1) {
                my $SpaceFrom = (split(/ /,$Spaces[$x])) [0];
                $SpaceFrom=~s/;//;
                $SpaceFrom=~s/\)+//;
            #print Writer1 $SpaceFrom."\n\n";
                push(@parents,$SpaceFrom);

        #        print "\n\n".$SpaceFrom."\n\n";
        #        print Writer "\n\n".$SpaceFrom."\n\n";

            }
    foreach my $x (1..@joins-1){
        #print "$joins[$i]"."\n\n";

            my $join = (split(/ on /i,$joins[$x])) [0];
            my $joinspace = (split(/ /i,$joins[$x])) [0];
            #print Writer "\n\n".$join."\n\n";   
            #print Writer1 $joinspace."\n\n";
            #"$joinspace\n\n";
             push(@parents,$joinspace);

        print Writer1"\n\n".$parents[$_]."\n\n";

    }

        }

        push @views, [$name, $type, $content, @parents, @children];

        $hashtable{$name}="[0]Name:$name
[1]Type:$type


[2]Content:$content

[3]Parents:@parents"."\n\n




".


"----------------------------";


}


print Writer "Key:$_ 
Value:
$hashtable{$_}\n" foreach (keys%hashtable);

#------------------------------------------------------------------------------

print_views(\@views);


exit;



#------------------------------------------------------------------------------
sub get_view {
    my $create_cmd = $_[0];
    my $tmp = (split(/ view | trigger | table /i, $create_cmd))[1];
    $tmp =~ s/^\s+//;
    my $view = (split(/\s+/, $tmp))[0];
    return $view;
}
#-----------------------------------------------------------------------------
sub get_type{
    my $create_cmd = $_[0];
    my $tmp = (split(/ replace /i, $create_cmd))[1];
    $tmp =~ s/^\s+//;
    my $view = (split(/\s+/, $tmp))[0];
    return $view;
}
#-----------------------------------------------------------------------------
sub get_parents {

}
sub get_children {



    }



get_children();


close Writer1;
close Writer;

This is how a chunk of data i have to parse looks like :

create or replace view MINA_TI_GRP_V
as
select NVL(max(t1.interval_group),(select dm_group from sdate_dm_grp_v)) AS DM_GROUP,
  (t2.interval_number) INTERVAL_NUMBER ,  t2.time_interval_s
  from  MINA_INTERVAL_CONTROL t2
  left join DM_TI_GRP_DATE_TIME t1 on t2.time_interval_s >= t1.time_interval_s
  group by t2.interval_number ,  t2.time_interval_s
  order by t2.interval_number;

Where is your Perl code? We need a minimal reproducible example added to the question so we know what you're trying to do — Chris Turner
I asked you for perl code And, edit your question instead of puting some code in comments. It's unreadable. — Toto

Chris Turner Chris Turner · Accepted Answer · 2017-07-26T14:16:10

If you want to easily find out what the parents are for an entry in %hashtable, you'll find it much easier if you store the data as another hash rather than one giant string like this...

$hashtable{$name}={"Name" => $name, "Type" => $type, "Parents" => \@Parent};

Then you can reference $hashtable{$key}->{"Parents"} to get an array ref that contains the parents for that data entry which you could use like this...

foreach my $parent (@{$hashtable{$key}->{"Parents"}})
  {
  if(defined($hashtable{$parent}))
    {
    # Parent exists in hashtable
    }
  else
    {
    # Parent does not exist in hashtable
    }
  }

Updating and creating new elements in a hash table

1 Answers