帮帮我。。在数据库中我使用插入写入的字符能显示中文，但是用ph

在数据库中我使用插入写入的字符能显示中文，但是用php语句写的就乱了

<?php
/* $link=mysqli_connect('localhost','root','6322482','fund');
if(!mysqli_connect_errno($link)){
echo "ok";
}else{
echo"bad";
} */ //过程化的连接数据库
header("content-type:text/html;charset=utf-8");
$db=new mysqli('localhost','root','6322482','fund');
if($db->connect_errno){
echo "problem";
}else{
echo "success";
};
$sql="insert into users(username,email,password) values ('曹欣','caoxin0222@126.com','13630264286')";
if(mysqli_query($db,$sql)){
echo "new record created successfully";
}else{
echo "Error:".$sql."<br>".mysql_error($db);
};
$sq="insert into two (name) values ('洗车110');";
if(mysqli_query($db,$sq)){
echo "ok";
}else{
echo "fuck";
};
$db->close(); //或者mysql_close($con);