THINKPHP限制今天提交的数据不超过几条

   代码如下，主要是看SQL的部分：

$where["client_id"] = $data["client_id"];
			$where["_string"] = "FROM_UNIXTIME(createAt,"%Y-%m-%d")="".date("Y-m-d", time()).""";
			$PostTimesToday = M("feedback")->where($where)->count();
			//提交次数超过5次则不准提交
			if($PostTimesToday > C("FEEDBACK_DAY_LIMIT"))
			{
			$this->throwException("PASS_THE_LIMIT", "OTHER");
			}