fix quoting in mysql

the old mechanism did not consider undefined values NULL, and failed
for empty strings and for stuff that looked vaguely like numbers, but were
not well-formed numbers

lib/DBDish/mysql.pm6

@@ -145,11 +145,16 @@ class DBDish::mysql::StatementHandle does DBDish::StatementHandle {
         my $statement = $!statement;
         while @params.elems>0 and $statement.index('?')>=0 {
             my $param = @params.shift;
-            if $param ~~ /<-[0..9.]>/ {
-                $statement .= subst("?", self.quote($param.Str)); # quote non numerics
+            if $param.defined {
+                if $param ~~ Real {
+                    $statement .= subst("?", $param.Str);
+                }
+                else {
+                    $statement .= subst("?", self.quote($param.Str));
+                }
             }
             else {
-                $statement .= subst("?", $param); # do not quote numbers
+                $statement .= subst("?", 'NULL'); # do not quote numbers
             }
         }
         # warn "in DBDish::mysql::StatementHandle.execute statement=$statement";

t/10-mysql.t

@@ -39,9 +39,9 @@ use DBIish;
 my $mdriver       = 'mysql';
 my $host          = 'localhost';
 my $port          = 3306;
-my $database      = 'zavolaj';
-my $test_user     = 'testuser';
-my $test_password = 'testpass';
+my $database      = 'moritz4';
+my $test_user     = 'moritz';
+my $test_password = 'aeNohh4a';
 my $table         = 't1';
 
 #-----------------------------------------------------------------------

t/25-mysql-common.t

@@ -8,9 +8,9 @@ my $*mdriver = 'mysql';
 my %*opts = ().hash;
 %*opts<host>       = 'localhost';
 %*opts<port>       = 3306;
-%*opts<database>   = 'zavolaj';
-%*opts<user>       = 'testuser';
-%*opts<password>   = 'testpass';
+%*opts<database>   = 'moritz4';
+%*opts<user>       = 'moritz';
+%*opts<password>   = 'aeNohh4a';
 
 # Detect and report possible errors from eval of the common test script
 warn $! if "ok 99-common.pl6" ne eval slurp 't/99-common.pl6';