Update scalar variable globally inside if statement in Perl? - perl

Question

I'm trying to update a variable declared and used outside of a series of if / elsif / else statements, and updating it within the series. Is there a functional way to make this sorting/updating variable work?
my $daterange = 'initial';
if ($in{from_date} & $in{to_date}) {
my $daterange=~"AND (date BETWEEN '$fromdate' and '$todate')";
}
elsif ($in{from_date}) {
my $daterange=~"AND (date > '$fromdate')";
}
elsif ($in{to_date}) {
my $daterange=~"AND (date < '$todate')";
}
else {
my $daterange=~"blank";
}
print $daterange;

Answer 1

my creates a new variable. That means that inside your "then` clauses, you create a new variable, then assign a string to it. You never use that variable again!
You want to assign to the existing variable, so stop creating new ones with the same name.
There are numerous other problems with your code:
Your code suffer from SQL injection bugs.
You used =~ to assign to a variable when the assignment operator is =.
You used & to check if two value are true when the logical-AND operator is &&.
You used "blank" to create an empty string when it doesn't.
You sometimes use $in{from_date} and sometimes $fromdate.
You sometimes use $in{to_date} and sometimes $todate.
You assign an initial value (initial) to $daterange that you never end up using.
You have some useless parentheses in your SQL.
Fixed:
my $daterange;
if ($in{from_date} && $in{to_date}) {
$daterange = " AND (date BETWEEN ".$dbh->quote($in{from_date})." AND ".$dbh->quote($in{to_date}).")";
} elsif ($in{from_date}) {
$daterange = " AND date > ".$dbh->quote($in{from_date});
} elsif ($in{to_date}) {
$daterange = " AND date < ".$dbh->quote($in{to_date});
} else {
$daterange = "";
}

Answer 2

Delete all my except the first one.
This prevents one local variable being introduced for each {}, which is then unknown outside.
That way, the accesses inside the {} will affect your global variable.
As c3st7n noted (thanks), you will also have to doublecheck what you actually do to your variable, it is likely that it is not what you intended. I.e. you probably want to use = instead of =~.