insert data into Nested Hash

poqui has asked for the wisdom of the Perl Monks concerning the following question:

This is kind of a newbie question.

I am collecting statistics from a database for data profiling.
I have created a 4 deep hashes within hashes to hold those stats, as such:

$a={NUM_NULL => 0,
    DISTINCT => 150,
    NUM_ROWS => 2000};
$b={PRO_NUMBER => \%a};
$c={AC_SHIPMENT => \%b};
%Profileshoh = (IC_STAGE => \%c);
[download]

While I have good success obtaining the statistics, I am only getting the last value loaded into the hash structure back when I attempt to print it out.

I suspect my problem is in the loop where I am loading the data. I think I may be re-defining the whole hash at that point, but I can't find an example that shows me what I want to do.

code after readmore

#!/usr/bin/perl -w
use DBI;

$dbh = DBI->connect("dbi:Oracle:XXXX","XXXXXX","XXXX",
                                { AutoCommit => 0,
                                  RaiseError => 1,
                                 PrintError => 1 })
                        or die "can't connect to database:",
                        $DBI::errstr, "\n";
$sth = $dbh->prepare("select 'IC_STAGE', t.table_name, column_name
  from user_tables t, user_tab_columns c
  where c.table_name = t.table_name
   AND t.table_name = 'AC_SHIPMENT'
   AND column_name in ('ACT_DELIVERY_TSP', 'CONS_NATL_ACCT_NBR',
                     'PICKUP_UNIT_ID')");
$sth->execute();

while (@row = $sth ->fetchrow_array())  {
    push @ListoTabCols, [@row];
}

$dbh ->disconnect();

print "disconnected\n";

for $i ( 0 .. $#ListoTabCols ) {
    print "reconnecting\n";
    $dbh = DBI->connect("dbi:Oracle:XXXX","XXXX","XXXX",
                                { AutoCommit => 0,
                                  RaiseError => 1,
                                 PrintError => 1 })
                    or die "can't connect to database:",
                    $DBI::errstr, "\n";
    $prow = $ListoTabCols[$i];
    print "row $i : $prow->[0] $prow->[1] $prow->[2]\n";
    @returno = $dbh->selectrow_array("select min($prow->[2]) from $pro
+w->[1]");
    
    $dbh ->disconnect();
    print "disconnected\n";
# HERE IS THE INSERT INTO THE HASH *************
    print "returned value: $returno[0]\n";
    %Profileshoh = ($prow->[0] => {
        $prow->[1]=>{
            $prow->[2]=>{
                MIN_VALUE=>$returno[0]
            }
        }
    })
}

while ( ($schemata, $tablas) = each %Profileshoh ) {
    print "$schemata: ";
    while ( ($tabla, $colums) = each %$tablas ) {
        print "$tabla: ";
        while ( ($colum, $measures) = each %$colums ) {
            print "$colum: ";
            while ( ($measure, $value) = each %$measures ) {
                print "$measure = $value ";
            }
        }
    }
    print "\n";
}

exit;
[download]

Comment on insert data into Nested Hash Select or Download Code

Replies are listed 'Best First'.
Re: insert data into Nested Hash by Roy Johnson (Monsignor) on Jul 15, 2004 at 18:12 UTC
Your hash description is alarming. You do know that `\%a` is unrelated to hash ref `$a`, right? What you call an insert into the hash is a complete re-assignment of the hash. I think you're making very clunky use of hashes, and perhaps a review of `perlreftut` would be helpful. At the least, you can change your statement to an insert like so: `$Profileshoh{$prow->[0]} = { $prow->[1]=>{ $prow->[2]=>{ MIN_VALUE=>$returno[0] } } };` [download] but I haven't determined whether that's What You Really Want. Update: I think you Really Want `$profileshoh{$prow->[0]}{$prow->[1]}{prow->[2]}{MIN_VALUE} = $returno[ +0];` [download] We're not really tightening our belts, it just feels that way because we're getting fatter.	[reply] [d/l] [select]
Re^2: insert data into Nested Hash by poqui (Deacon) on Jul 15, 2004 at 18:33 UTC
Your hash description is alarming. You do know that \%a is unrelated to hash ref $a, right? Whoops! No I didn't realize that. I see now. $a is a reference to an anoymous hash, and \%a is the reference to a named hash, named %a. And YES! Your Update was exactly what I really wanted. Thank You! :-)	[reply]
Re: insert data into Nested Hash by ccn (Vicar) on Jul 15, 2004 at 18:03 UTC
Please note the difference between: `$a={NUM_NULL => 0, DISTINCT => 150, NUM_ROWS => 2000}; $b={PRO_NUMBER => $a }; $c={AC_SHIPMENT => $b}; %Profileshoh = (IC_STAGE => $c );` [download] and `$a={NUM_NULL => 0, DISTINCT => 150, NUM_ROWS => 2000}; $b={PRO_NUMBER => {%$a} }; $c={AC_SHIPMENT => {%$b}}; %Profileshoh = (IC_STAGE => {%$c} );` [download] In the first case you share the data between the hashes. In the second case each hash have it's own data	[reply] [d/l] [select]