Hey all,

I'm writing a fairly nasty piece of code atm which will read in a table from a database (using Sybase::DBlib) and hash it based on user-provided keys (it has to be done this way - I need to read a lot of tables and need the reusability).

I am storing each row's data as it comes from the DB in a temporary hash keyed on column name, and want to append this to the master hash keyed on the specified columns (there could currently be up to 5 keys).

My problem comes when appending the data to the master hash - because the number of keys is unknown, I can think of no "clean" way to append the data. I have experimented a little with recursion, to no avail, and am left currently with long and ugly code which copes with up to 3 keys - which isn't enough. Is there an "easier" way to place this data into the hash?

Any suggestions would be appreciated.

My code atm is as follows: 

# download the data from the db, using a trapped alarm in case of db
# failure (prevents an infinite wait).
alarm 600;
local $SIG{ALRM} = sub { return $FALSE; };

$dbh -> dbcmd("SELECT * FROM $table");
$dbh -> dbsqlexec;
$dbh -> dbresults;

# get the column names for the data
my @columnames;
for (my $i = 0; $i <= $dbh -> dbnumcols; $i++)
  {
      push (@columnames, $dbh -> dbcolname($i));
    }
                
# write the table data to a hash
my %tableData;
while (my @data = $dbh -> dbnextrow)
    {
        my %tblData;
        for (my $i = 0; $i < $#columnames; $i++)
            {
                $data[$i] =~ s/^\s|\s$//g;
                $tblData{$columnames[$i+1]} = $data[$i];
            }
                                    
                                    
        # get the data keys and hash accordingly
        my $hashkey = $tblData{$key};
        delete $tblData{$key};
                                        
        if (defined $key3)
          { # if there are 3 keys
              my $hashkey2 = $tblData{$key2};
                my $hashkey3 = $tblData{$key3};
                delete $tblData{$key2};
                delete $tblData{$key3};

                %{$tableData{$hashkey}{$hashkey2}{$hashkey3}} = %tblDa
+ta;
            }
        elsif (defined $key2)
          { # if there are 2 keys
              my $hashkey2 = $tblData{$key2};
                delete $tblData{$key2};
                        
                %{$tableData{$hashkey}{$hashkey2}} = %tblData;
      }
        else
          { # there's only 1 key
              %{$tableData{$hashkey}} = %tblData;
            }
     }
                
return \%tableData;

[download]

I'm sure there must be a better way to do this, but I really can't see it.

Thanks -- Foxcub.

In reply to Recursive hash assignment by Tanalis

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