Hi ,

     my $var = q("string (12" or 1 foot or 1') into 6" MySQL varchar")
+;
     $var =~ s/(?<!^)"(?!$)/""/g;
     print "[$var]\n";

     __END__

     ["string (12"" or 1 foot or 1') into 6"" MySQL varchar"]
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The look_ahead and look_behind negative assertion on ^ and $ shall do the match only in the other places of the string