Show us the code of your sub insert {...}, because that is where the string or number distinction has to be made. Also consider how you will try to insert a string that looks_like_a_number, like "3".

Is there any reason why you aren't using DBI placeholders instead?

I didn't know of the existence of DBI placedholders. :( . Lolz. Thanks, just saved me a couple of weeks worth of coding. I'm new to databases :(.

That's almost correct. $ will match an optional newline as well, so both "5" and "5\n" are valid. Better to use \z

print "1. number\n" if "5" =~ /^\d+$/;
print "1. number and newline\n" if "5\n" =~ /^\d+$/;

print "2. number\n" if "5" =~ /^\d+\z/;
print "2. number and newline\n" if "5\n" =~ /^\d+\z/
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Update
The advice to use a \z fixes the problem of bad data being submitted, but it might block otherwise good data, depending on the input source. Data read from a filehandle could have the newline present, without it being from a misbehaving user.
chomping the field in question is a better approach than being stricter with the regex.

If you're using DBI and placeholders then it should figure out the numericalityness of values and send them to the database correctly. If it's not you can use the bind_param method on a statement handle to explicitly set the SQL type a given placeholder should have. See the DBI docs for more details.

You should also know about Scalar::Util's function, looks_like_number.

That shouldn't be an issue if you're using placeholders. DBI knows if it's suppose to be an number or a string based on information it obtains from the database.

sub escape_name {
   my $t = @_ ? $_[0] : $_;
   $t =~ s/`/``/g;
   return "`$t`";
}

my $table = 'sometable';
my @cols = qw( id name );
my @vals = qw( 3 somename );

my $stmt = "INSERT INTO "
         . escape_name($table)
         . " ("
         . join(', ', map escape_name, @cols)
         . ") VALUES ("
         . join(', ', (?) x @cols)
         . ")";

my $sth = $dbh->prepare($stmt);

$sth->execute(@vals);
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I'm using MySQL's escape mechanism for table names and column names. I don't know if DB2 uses the same mechanism.

$dbh->quote_identifier is the portable version of escape_name

my $table = 'sometable';
my @cols = qw( id name );
my @vals = qw( 3 somename );

my $stmt = "INSERT INTO "
         . $dbh->quote_identifier($table)
         . " ("
         . join(', ', map { $dbh->quote_identifier($_) } @cols)
         . ") VALUES ("
         . join(', ', (?) x @cols)
         . ")";

my $sth = $dbh->prepare($stmt);

$sth->execute(@vals);
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Now consider the following code (use lines removed for brevity):

Lastly, consider this piece of code forcing the string or integer into integer context. Notice the exponentiation doesn't throw an error because the input was forced into integer context.

my $x = <STDIN>;
$x *= 1;
print "String\n" if ($x =~ /\w/);
print "Integer\n" if ($x =~ /\d/);
print $x**$x ."\n";
__OUTPUT__
2
String
Integer
4
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Note: The reason its a string and an integer is in the case of \w (which is what the regex uses), it checks for [0-9a-zA-Z] as well.

unless ($val1=~/\A[-+]?\d+\.?\d*\Z/) {
  #quote here $val1, for example:
  $val1=$dbh->quote($val1);  
}
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my $sth = $dbh->prepare(q{
    INSERT INTO sales (product_code, qty, price) VALUES (?, ?, ?)
  }) or die $dbh->errstr;
  while (<>) {
      chomp;
      my ($product_code, $qty, $price) = split /,/;
      $sth->execute($product_code, $qty, $price) or die $dbh->errstr;
  }
  $dbh->commit or die $dbh->errstr;
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DBI is OK has some sample code you might enjoy.