# Untested
my $ScanString =~ /
                       (                         # start of capture      
                         INSERT
                         .*?                     # the ? after * means the shortest possible match
                       )                         # end of capture
                       (?:\(|values|select|;)      # (?: thing ) groups without capturing
                     /six; # s allows .* to match across several lines. x allows spaces and comments in the regex
my $substring = $1;

my $found_doc = $substring =~ /\b doc \b/ix; # \b means boundary, so beginning or end of a word