$query = MysqL_query("SELECT * From table");
$rows = array();
while($row = MysqL_fetch_assoc($query)) {
    $rows[] = $row;
}
print json_encode($rows);

如果你没有json_encode,请在上面的代码之前添加：

if (!function_exists('json_encode'))
{
  function json_encode($a=false)
  {
    if (is_null($a)) return 'null';
    if ($a === false) return 'false';
    if ($a === true) return 'true';
    if (is_scalar($a))
    {
      if (is_float($a))
      {
        // Always use "." for floats.
        return floatval(str_replace(",",".",strval($a)));
      }

      if (is_string($a))
      {
        static $jsonReplaces = array(array("\\","/","\n","\t","\r","\b","\f",'"'),array('\\\\','\\/','\\n','\\t','\\r','\\b','\\f','\"'));
        return '"' . str_replace($jsonReplaces[0],$jsonReplaces[1],$a) . '"';
      }
      else
        return $a;
    }
    $isList = true;
    for ($i = 0,reset($a); $i < count($a); $i++,next($a))
    {
      if (key($a) !== $i)
      {
        $isList = false;
        break;
      }
    }
    $result = array();
    if ($isList)
    {
      foreach ($a as $v) $result[] = json_encode($v);
      return '[' . join(',',$result) . ']';
    }
    else
    {
      foreach ($a as $k => $v) $result[] = json_encode($k).':'.json_encode($v);
      return '{' . join(',$result) . '}';
    }
  }
}