mysql数据库数据库不能添加NULL值,该怎么解决

mysql数据库不能添加NULL值
数据都验证了，但是不能给数据添加NULL值，报错如下：

Column 'loumiandijia' cannot be null

其他数据在为空是用NULL都不行

代码如下

<?php
require ('inc/config.php');
$page_title = '住宅数据添加-feige数据中心';
include ('inc/header.php');
require (MYSQL);
if ($_SERVER['REQUEST_METHOD'] == 'POST') {	
	$trimmed = array_map('trim', $_POST);
	$errors = array();
	if (!empty($trimmed['tudi_id'])) {
		$tudi_id = mysqli_real_escape_string ($conn, $trimmed['tudi_id']);
	} else {
		$errors[] = '地块编号不能为空';
	}	
	if ( isset($trimmed['city']) && filter_var($trimmed['city'], FILTER_VALIDATE_INT, array('city' => 1)) ) {
		$city = mysqli_real_escape_string ($conn, $trimmed['city']);;
	} else {
		$errors[] = '请选择区域';
	}
	$weizhi = (!empty($trimmed['weizhi'])) ? mysqli_real_escape_string ($conn, $trimmed['weizhi']) : NULL;
	$yongtu = (!empty($trimmed['yongtu'])) ? mysqli_real_escape_string ($conn, $trimmed['yongtu']) : NULL;
	$rongjilv = (!empty($trimmed['rongjilv'])) ? mysqli_real_escape_string ($conn, $trimmed['rongjilv']) : NULL;
	$midu = (!empty($trimmed['midu'])) ? mysqli_real_escape_string ($conn, $trimmed['midu']) : NULL;
	$lvdi = (!empty($trimmed['lvdi'])) ? mysqli_real_escape_string ($conn, $trimmed['lvdi']) : NULL;	
	if(empty($trimmed['fabu_time'])) {
		$errors[] = '发布日期不能为空';
	} else {
		$fabu_time = mysqli_real_escape_string ($conn, $trimmed['fabu_time']);
	}
	if(empty($trimmed['chengjiao_time'])) {
		$errors[] = '成交日期不能为空';
	} else {
		$chengjiao_time = mysqli_real_escape_string ($conn, $trimmed['chengjiao_time']);
	}
	if(empty($trimmed['jiezhi_time'])) {
		$errors[] = '保证金截止时间不能为空';
	} else {
		$jiezhi_time = mysqli_real_escape_string ($conn, $trimmed['jiezhi_time']);
	}	
	if (is_numeric($trimmed['baozhengjin']) && ($trimmed['baozhengjin'] > 0)) {
		$baozhengjin = mysqli_real_escape_string ($conn, (float) $trimmed['baozhengjin']);
	} else {
		$errors[] = '请输入一个正确的竞买保证金（万元）';
	}
	if (is_numeric($trimmed['mianji_m']) && ($trimmed['mianji_m'] > 0)) {
		$mianji_m = mysqli_real_escape_string ($conn, (float) $trimmed['mianji_m']);
	} else {
		$errors[] = '请输入一个正确的占地面积（亩）';
	}
	if (is_numeric($trimmed['mianji_p']) && ($trimmed['mianji_p'] > 0)) {
		$mianji_p = mysqli_real_escape_string ($conn, (float) $trimmed['mianji_p']);
	} else {
		$errors[] = '请输入一个正确的占地面积';
	}
	if (is_numeric($trimmed['guihua_p']) && ($trimmed['guihua_p'] > 0)) {
		$guihua_p = mysqli_real_escape_string ($conn, (float) $trimmed['guihua_p']);
	} else {
		$errors[] = '请输入一个正确的规划建筑面积';
	}
	if (is_numeric($trimmed['qipaijia']) && ($trimmed['qipaijia'] > 0)) {
		$qipaijia = mysqli_real_escape_string ($conn, (float) $trimmed['qipaijia']);
	} else {
		$errors[] = '请输入一个正确的起拍价（万/亩）';
	}
	$chengjiaodanjia = (!empty($trimmed['chengjiaodanjia'])) ? mysqli_real_escape_string ($conn, (float) $trimmed['chengjiaodanjia']) : NULL;
	$chengjiazongjia = (!empty($trimmed['chengjiazongjia'])) ? mysqli_real_escape_string ($conn, (float) $trimmed['chengjiazongjia']) : NULL;
	$loumiandijia = (!empty($trimmed['loumiandijia'])) ? mysqli_real_escape_string ($conn, (float) $trimmed['loumiandijia']) : NULL;
	$yijialv = (!empty($trimmed['yijialv'])) ? mysqli_real_escape_string ($conn, $trimmed['yijialv']) : NULL;
	$jingderen = (!empty($trimmed['jingderen'])) ? mysqli_real_escape_string ($conn, $trimmed['jingderen']) : NULL;
	$churang_p = (!empty($trimmed['churang_p'])) ? mysqli_real_escape_string ($conn, (float) $trimmed['churang_p']) : NULL;
	$dituweizhi = (!empty($trimmed['dituweizhi'])) ? mysqli_real_escape_string ($conn, $trimmed['dituweizhi']) : NULL;
	$xuzhi = (!empty($trimmed['xuzhi'])) ? mysqli_real_escape_string ($conn, $trimmed['xuzhi']) : NULL;
	if ( isset($trimmed['is_cheng']) && is_numeric($trimmed['is_cheng']) && ($trimmed['is_cheng'] >= 0) ) {
		$is_cheng = mysqli_real_escape_string ($conn, $trimmed['is_cheng']);;
	} else {
		$errors[] = '请选择交易是否成功';
	}	
	
	if (empty($errors)) {
		$q = 'INSERT INTO f_tudi (tudi_id, city_id, weizhi, yongtu, rongjilv, midu, lvdi, fabu_time, chengjiao_time, jiezhi_time, baozhengjin, mianji_m, mianji_p, guihua_p, qipaijia, chengjiaodanjia, chengjiazongjia, loumiandijia, yijialv, jingderen, churang_p, dituweizhi, xuzhi, is_cheng) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)';