请教怎么用正则验证or1=1

$a = array(
  "or 1 = 1",
  "Or 1 = 1",
  "or 3 =3",
  "or now() = now()",
  "or 'a' = 'a'",
);

foreach($a as $s)
  echo $s, " :\t\t", preg_match('/or\b.+(\b\w+\b)[^=]*=.*\1/i', $s), PHP_EOL;

or 1 = 1 :		1
Or 1 = 1 :		1
or 3 =3 :		 1
or now() = now() :	1
or 'a' = 'a' :		1