Have you actually tested your string replacements? If you look at perlre, you will find that ^foo+ will only match foo, fooo and so on, but never foobar.

Please show a self-contained short example that demonstrates your problem. The code as you posted it does not work, so we can't really help you there.

It might be almost enough to just replace every % with (?:.*), but you will still need to understand how to deal with an SQL string that already contains * for example.

I do not understand your overall question.

However, some specific comments on the OPed regexes:

• Inside and at the very beginning of a character class, the  ^ regex metacharacter produces class "inversion", i.e., the class matches any character not in the class. So  [^$find1] is the same as  [^%] and matches any character that is not a  '%' character.
• Outside a character class, the  ^ metacharacter asserts the beginning of the string (if the  /m regex modifier is not used). So  [^$find1]?^ is the same as  [^%]?^ and matches zero or one of any character that is not a  '%' and that is before the beginning of the string. Effectively, it matches the beginning of the string and a  '^' character is always inserted at the beginning of the string by the substitution.
• The expression  [$find1]?$ matches zero or one  '%' characters at the end of the string (or before a newline at the end of the string). Effectively, a  '+' character is always inserted at the end of the string by the substitution.

Update:

c:\@Work\Perl\monks>perl -wMstrict -le
"my $field2_b = 'abcd';
 ;;
 my $find1 = '%';
 if ($field2_b ne '') { s/[^$find1]?^/\^/, s/[$find1]?$/+/ for $field2
+_b };
 print qq{'$field2_b'};
"
'^abcd+'
[download]

#!/usr/bin/perl --
use strict;
use warnings;
use Data::Dump qw/ dd /;

Main( @ARGV );
exit( 0 );

sub Main {
    MainOne();
    MainToo();
}
sub MainOne {
    my @fields = ( 'I foo', 'foo who?', 'the foo and the moo' );
    my @querys = qw/  foo%    %foo%    %f%o%  /;
    for my $field ( @fields ) {
        for my $search ( @querys ) {
            my $re = WildcardRe( $search );
            if( $field =~ m{$re}i ) {
                dd( { andthe => $field, has => $search, says => $re } 
+);
            }
        }
    }
} ## end sub Main

sub WildcardRe {
    ## todo update with Regexp::Wildcards
    my( $search ) = @_;
    my @parts = split /%/, $search;
    $_ = quotemeta( $_ ) for @parts;
    my $re = join '.+', @parts;
    $re = '^' . $re . '$';
    return $re;
} ## end sub WildcardRe

sub MainToo {
    my @fields = ( 'I foo', 'foo who?', 'the foo and the moo' );
    my @querys = qw/  foo%    %foo%    %f%o%  /;
    @querys = map { [ $_, WildcardRe( $_ ) ]; } @querys;
    for my $field ( @fields ) {
        for my $query ( @querys ) {
            my( $search, $re ) = @$query;
            if( $field =~ m{$re}i ) {
                dd( { andthe => $field, has => $search, says => $re } 
+);
            }
        }
    }
} ## end sub MainToo
[download]

ppi_dumper can tell you what manual to look up the basic perl syntax in ... like perlsyn ... example of this Re: use constant usage clarification (Deparse)

My understanding of % in SQL is that is corresponds to .* not .+.