What's failing in my Perl script? MySQL/getopt - mysql

Question

I wrote a script where I'm passing (optional, I hope!) command line arguments and sending them to a MySQL query. If any are omitted I want the query to basically ignore that argument. If I pass all 3, my query is working. If I pass the second (an integer) and the third (a letter) the script also works. But if I omit either the int or the letter I get no results.
I tried to fix this by using ISNULL and Coalesce in my MySQL query as I'm not sure if the declared variable is null or empty if I don't explictly pass them in my commandline argument.
Currently it works if I pass "Perl Script.pl -s Hockey -i 10 -l h, or
"Perl Script.pl -i 20 -l z", but fails under any other iteration of the 3 arguments.
What I want to know is
1. Did I make the arguments optional as I intended? Should I be using getopts instead of getopt?
2. What do I need to change in my MySQL query to get it to work as I intended? Why aren't ISNULL or Coalesce working?
3. Is anything else incorrect with the way I'm passing or passing the data?
#!/usr/bin/perl -w
use warnings;
use DBI;
use Getopt::Std;
use strict;
getopt('s:il');
our ($opt_s);
our ($opt_i);
our ($opt_l);
my $sport_search;
if ($opt_s) ($sport_search=$opt_s);
my $integer_search;
if ($opt_i=~m/\d+/) {$integer_search=$opt_i};
my $letter_search;
if ($opt_l =~m/^[a-zA-Z]$/) {$letter_search=$opt_l};
my $g_hash = function1($sport_search,$integer_search,$letter_search);
my $string = "Just a string!";
if (&function2($g_hash,$string) != 0) {
print "No values found for '$sport_search'","\n";
};
sub function1 {
my ($lsport_search,$linteger_search,$lletter_search) = #_;
our $dbh = DBI->connect{"dbi:mysql:dbname=database", "root", "password")
or die $DBI::errstr;
my $sql = "SELECT * from Players_Sport where Sport like '$lsport_search' AND length(Player)<=ISNULL('$linteger_search',20) AND Player between 'a' and ISNULL('lletter_search",'z')";
my $hash_ref = $dbh->selectall_hashref($sql, 'Player')
or die $DBI::errstr;
$dbh->disconnect
or warn "Disconnection failed: $DBI::errstr\n";
return $hash_ref;
}
sub function2 {
my ($l_hash,$variable_two) = #_;
my $hashvalue=();
if(keys $l_hash == 0) {
$hashvalue = -1;
}
else {$hashvalue = 0;
print "$_\n" for (keys %$l_hash);
};
return $hashvalue;
}

Answer 1

There are some problems in your query:
my $sql = "SELECT * from Players_Sport where Sport like '$lsport_search'
AND length(Player)<=ISNULL('$linteger_search',20)
AND Player between 'a' and ISNULL('lletter_search",'z')";
Even if $linteger_search and $lletter_search are undefined in Perl, they will never be NULL in SQL because you have put quotes around them. In MySQL, '' is not the same as NULL.
You also have some typos: 'lletter_search" should be '$lletter_search' Note you must end the quoted string with the same type of quotes that you started it with, but you started with single-quote and ended it with double-quote (actually, I'm surprised it didn't throw an SQL error).
You also forgot the $ variable prefix before lletter_search.
It's more common to build the SQL string dynamically, including search terms only when your search criteria are non-null.
my $sql = "SELECT * from Players_Sport where true ";
if ($lsport_search) {
$sql .= " AND Sport like '$lsport_search' ";
}
if ($linteger_search) {
$sql .= " AND length(Player) <= $linteger_search";
}
if ($lletter_search) {
$sql .= " AND Player between 'a' and '$lletter_search'";
}