in reply to Loader script - Design question

You don't need selectall_hashref if you're just looking at one record, which is what you should be doing if you have an ID. You need selectrow_hashref.

It might be useful if you could say what you mean by "the result is messed"

The selectrow_hashref should give you something like: 

$ref = {
         'column_1' => 'foo',
         'column_2' => 'bar',
         'id' => 12345
       };

[download]

At which point you can just check whether your column_1 from the CSV file matches $ref->{column_1} etc.

Replies are listed 'Best First'.
Re^2: Loader script - Design question
by artanisace (Initiate) on Feb 23, 2016 at 12:38 UTC

    This is what I meant by the result is messed, if I do this for example:

    # Update DB with file content
my @keys = ('ID');
my $hash = $dbh->selectall_hashref("SELECT * FROM users", \@keys);
print Dumper \$hash;

    [download]

    This happens:

    http://postimg.org/image/3rhdfupnx/

    If I add more values to @keys, the 'chain' of hashref gets bigger... and I don't really know what's happening :S

[reply]
[d/l]
      the 'chain' of hashref gets bigger.

      That's what selectall_hashref does

      The $key_field parameter defines which column, or columns, are used as keys in the returned hash. It can either be the name of a single field, or a reference to an array containing multiple field names. Using multiple names yields a tree of nested hashes.

      What structure do you want ?

      poj
[reply]

        I want something like I have when I use text::CSV to read the file and turn it into hashref:

        # Read file from path
my @rows; 
my $csv = Text::CSV->new ( { binary => 1, sep_char => "\t" } )
                   or die "Error creating TSV object: ".Text::CSV->err
+or_diag ();
 
open my $fh, "<:encoding(utf8)", "$filename"
                    or die "Error reading CSV file: $!";

$csv->column_names ($csv->getline ($fh)); # Get header names
while ( my $record = $csv->getline_hr( $fh ) ) {
     # Process record
     push @rows, $record;
}
$csv->eof or $csv->error_diag();
close $fh;

print Dumper \@rows;

        [download]

        This is the output after reading the file:

        $VAR1 = [
          {
            'ID' => '4564',
            'Date' => '4-05-1986,
            'Name' => 'Mengano'
          }
       ];

        [download]
[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom