PHP程序中添加数据库信息，添加不进去，也不报错，代码看了也是正确的。求大神指教
<?php
session_start();
include "../config.php";
if(!isset($_SESSION['username'])){
echo "<script type=\"text/javascript\"> window.location.href=\"login.php\" </script>";
}
if(isset($_GET['add'])){
$xm=$_POST['xm'];
$password=$_POST['password'];
$xb=$_POST['xb'];
$zzbm=$_POST['zzbm'];
$dhhm=$_POST['dhhm'];
$sql="insert into yh set xm='$xm',password='$password',xb='$xb',zzbm='$zzbm',ddhm='$dhhm'";
$insert=$conn->query($sql);
//echo $insert;
}
?>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>用户信息添加</title>
<link rel="stylesheet" type="text/css" href="../layui-v2.6.7/layui/css/layui.css"/>
<script src="../layui-v2.6.7/layui/layui.js" type="text/javascript" charset="utf-8"></script>
</head>
<body>
<form class="layui-form" action="yhadd.php?add=1" method="post">
<div class="layui-form-item">
<label class="layui-form-label">姓名</label>
<div class="layui-input-block">
<input type="text" name="xm" required lay-verify="required" placeholder="请输入用户名" autocomplete="off" class="layui-input">
</div>
</div>
<div class="layui-form-item">
<label class="layui-form-label">登录密码</label>
<div class="layui-input-inline">
<input type="password" name="password" required lay-verify="required" placeholder="请输入密码" autocomplete="off" class="layui-input">
</div>
<div class="layui-form-mid layui-word-aux">为保证安全，建议密码为数字加字母</div>
</div>
<div class="layui-form-item">
<label class="layui-form-label">性别</label>
<div class="layui-input-block">
<input type="radio" name="xb" value="男" title="男" required="required">
<input type="radio" name="xb" value="女" title="女" required="required">
</div>
</div>
<div class="layui-form-item">
<label class="layui-form-label">组织部门</label>
<div class="layui-input-block">
<input type="text" name="zzbm" required lay-verify="required" placeholder="请填写手机号码" autocomplete="off" class="layui-input">
</div>
</div>
<div class="layui-form-item">
<label class="layui-form-label">电话号码</label>
<div class="layui-input-block">
<input type="text" name="dhhm" required lay-verify="required" placeholder="请填写所在组织" autocomplete="off" class="layui-input">
</div>
</div>
<div class="layui-form-item">
<div class="layui-input-block">
<button class="layui-btn" lay-submit lay-filter="formDemo">立即提交</button>
<button type="reset" class="layui-btn layui-btn-primary">重置</button>
</div>
</div>
</form>
<script >
//使用layui的多个模块
layui.use(['form','laydate','layer'],function(){
var form = layui.form;
var layer = layui.layer;
//各种监听事件
<?php if($insert){?>
layer.msg('添加用户成功');
<?php }?>
});
</script>
</body>
</html>
您的sql语句有错误哦！！