Your question leaves room for interpretation ;-) My interpretation is, you want to put all combinations into a four column sized table. The following example unfolds the loops using a silly glob hack - don't do that for production code! There are modules on CPAN (e.g. iterator) to create multi-level for-loops.

use strict;
use warnings;


my $hash_of_excel = [
                     {
                      col1 => "value1",
                      col2 => "value2",
                      col3 => "value3|value4",
                      col4 => "value5|value6|value7",
                     },
                     {
                      col1 => "value8",
                      col2 => "value9",
                      col3 => "value10|value11|value12",
                      col4 => "value13|value14|value15",
                     },
                     {
                      col1 => "value16|value17",
                      col2 => "value19|value18",
                      col3 => "value20",
                      col4 => "value21",
                     }
                    ];


foreach my $results (@$hash_of_excel){
  my $glob_expression;

  for my $colname( sort keys %$results){
    my @array  = split /\|/,$results->{$colname};
    $glob_expression .= '{' . join(',', @array) . '};';
  }

  chop $glob_expression;
  print "EXP: $glob_expression:\n";
  print "\t", join("\n\t",  glob $glob_expression), "\n\n";
}
[download]

Result:

 EXP: {value1};{value2};{value3,value4};{value5,value6,value7}:
        value1;value2;value3;value5
        value1;value2;value3;value6
        value1;value2;value3;value7
        value1;value2;value4;value5
        value1;value2;value4;value6
        value1;value2;value4;value7

EXP: {value8};{value9};{value10,value11,value12};{value13,value14,valu
+e15}:
        value8;value9;value10;value13
        value8;value9;value10;value14
        value8;value9;value10;value15
        value8;value9;value11;value13
        value8;value9;value11;value14
        value8;value9;value11;value15
        value8;value9;value12;value13
        value8;value9;value12;value14
        value8;value9;value12;value15

EXP: {value16,value17};{value19,value18};{value20};{value21}:
        value16;value19;value20;value21
        value16;value18;value20;value21
        value17;value19;value20;value21
        value17;value18;value20;value21
[download]

#!/usr/bin/perl --
use strict; use warnings; use Data::Dump qw/ dd /;
my $record = {
    col1 => "value8",
    col2 => "value9",
    col3 => "value10|value11|value12",
    col4 => "value13|value14|value15",
};
dd( $record );
SomethingUnPipeModifyRecord( $record );
dd( $record );
dd( $record->{col4} );
dd( $record->{col4}[0] );

sub SomethingUnPipeModifyRecord {
    my( $rec ) = @_;
    for my $val( values %$rec ){
        my $newval = [ split /\|/, $val ];
        $val = $newval;
    }
    return $rec;
}
__END__
{
  col1 => "value8",
  col2 => "value9",
  col3 => "value10|value11|value12",
  col4 => "value13|value14|value15",
}
{
  col1 => ["value8"],
  col2 => ["value9"],
  col3 => ["value10", "value11", "value12"],
  col4 => ["value13", "value14", "value15"],
}
["value13", "value14", "value15"]
"value13"
[download]

That's right but my question was how would I know whether the particular record has more than one values or not without looping through them?

For example the col3 has more values but col2 has on value. I would like to skip the col2 from going through any loop if it has one value and proceed with the insert statements. If I have more than one values then I have to loop through them for each value to be inserted to the DB. Hope I am clearer this time.

I hope the Stackoverflow post is more coherent.

So, in the end you want to

insert into table (col1) values (value1)
insert into table (col1) values (value8)
insert into table (col2) values (value2)
insert into table (col2) values (value9)
insert into table (col3) values (value3)
...
insert into table (col4) values (value14)
insert into table (col4) values (value15)
[download]

Is that correct? You want to retrieve the data from the array of hashes organized in such a way to facilitate that.

The loop variable of your inner loop is $value yet the loop body does not use that variable. Try replacing $results there by $value.

update: This node should be reaped. I posted to the wrong thread... this is a reply to Re: Is is possible to use perl fork and ithreads within the same application

The reason for wanting to mix the two is that I have to open up 300+ connections to unique devices.

You don't tell what kind of connection that is, and what amount of code is involved interacting with those devices. Maybe you could make the connections into just (file)handles using pipe before forking, and IO::Select in the parent. If the creation and interaction with those devices is asynchronous (i.e. random wrt time), you could use an event based model using Event, EV or POE. That way your forked processes will be small enough, and will be returning claimed memory to the OS after execution. This is given with a lot of handwaving, of course; more of your code is required to give good advice.