Re^2: Storing data into hashes

[rkrish]

Hi, I have tried this but unable to see any data stored in hash. The query is valid and it is fetching the data.I have verified it.

sub loadSeqNbr
{
    my %SeqRec;
    my $SeqRecord = $lda->prepare("select seq_nbr,data_record from usa
+ge_inq" );
    $SeqRecord->execute()

    while ( my $data = $SeqRecord->fetchrow_hashref()) 
    {
        $SeqRec{$data->{seq_nbr}}=$data->{data_record};
    }

    print ("content of hash is %SeqRec \n");

}

output is:

content of hash is %SeqRec

[Corion]

Hashes don't interpolate in strings:

#!perl -w
use strict;

my %SeqRec;
print ("content of hash is %SeqRec\n");

I recommend to use Data::Dumper for debugging contents of variables:

use Data::Dumper;
my %SeqRec = (foo => 'bar');

print ("content of hash is " . Dumper \%SeqRec);

[rkrish]

is the way of storing data I have mentioned into hash is correct because i dont see any data actually stored in it. the output showed as :

contents of hash is $VAR1 = {
          '' => undef,
          'foo' => 'bar'

[Corion]

When I run the code I showed, I get different output:

use Data::Dumper;
my %SeqRec = (foo => 'bar');

print ("content of hash is " . Dumper \%SeqRec);

content of hash is $VAR1 = {
          'foo' => 'bar'
        };

Your output is at least missing the closing bracket. If you want to debug this, please show the full code you're running.

[roboticus]

rkrish:

A couple things:

• Have you put a print statement inside your while loop to verify that results are coming back?
• Have you tried using Data::Dumper to print the contents of $data in the loop?
• Some databases will return the column names in upper case (I'm looking at you Oracle!).

(Printing the contents of $data when read will show you if it's a case problem or not.)

...roboticus

When your only tool is a hammer, all problems look like your thumb.

[rkrish]

Hi, I have used print statement inside the while loop to print the content of data and also used Data::Dumper.The output is as follows

data returned is HASH(0x4e9574) 
data returned is HASH(0x4e9598) 
data returned is HASH(0x4e958c) 
data returned is HASH(0x4e961c) 
data returned is HASH(0x4e95b0) 
data returned is HASH(0x4e955c) 
data returned is HASH(0x4e94fc) 
data returned is HASH(0x4e9568) 
data returned is HASH(0x4e95e0) 
data returned is HASH(0x4e96d0) 
data returned is HASH(0x22d410) 
data returned is HASH(0x4e94e4) 
data returned is HASH(0x22d350) 
data returned is HASH(0x4e9574) 
data returned is HASH(0x4e9598) 
data returned is HASH(0x4e958c) 
contents of hash is $VAR1 = {
          '' => undef,
          'foo' => 'bar'
        };

The output of query in sql is as follows:

SQL> select seq_nbr,data_record from usage_inq;

SEQ_NBR DATA_RECORD
------------------ -----
               200 10
               145 10
               205 10
               450 10
              2227 10
              2386 10
               202 10
               204 10
               144 10
               472 10
              1042 10

SEQ_NBR DATA_RECORD
------------------ -----
              1261 10
               203 10
               504 10
               201 10
               503 10
16 rows selected.

SQL>

[roboticus]

But you didn't use Data::Dumper, so we can't see what the hash reference contains. If you used it you might see something like:

$VAR1={ COLUMN=>'value', COLUMN2=>'value2' }

So then you could see the names of the keys in your hash. As mentioned previously, you can't just do:

print "Foo %hash\n";

and expect to get anything useful from it.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

[cdarke]

Looks to me that you are printing the hash after the loop, not in the loop. The hash gets recreated for each row, you need to inspect it inside the loop.