php 判断是否有相同的ID，如果有就修改数据库字段，没有就插入数据库字段

header("Content-Type:text/html;charset=utf8"); 
header("Access-Control-Allow-Origin: *"); //解决跨域
header('Access-Control-Allow-Methods:POST');// 响应类型  
$link=mysql_connect("localhost","root","root"); 
mysql_select_db("business_card",$link); //选择数据库
mysql_query("SET NAMES utf8");//解决中文乱码问题
error_reporting(E_ALL & ~E_NOTICE);

header("Content-Type:text/html;charset=utf8");
if ($_FILES["file"]["error"] > 0)
{
echo "错误: " . $_FILES["file"]["error"] . "
";
}
else
{
}
$if_up_img = $_POST['if_up_img'];
//提交文本
if($if_up_img==0){
$nickname = $_POST['nickname'];
$head = $_POST['head'];
$phone = $_POST['phone'];
$mail = $_POST['mail'];
$name = $_POST['name'];
$sex = $_POST['sex'];
$wx = $_POST['wx'];
$region = $_POST['region'];
$position = $_POST['position'];
$geology = $_POST['geology'];
$detail = $_POST['detail'];
$now_time = $_POST['now_time'];
$id = $_POST['id'];

    $q = "SELECT * FROM business_card"; //SQL查询语句 SELECT * FROM 表名
    $result = mysql_query("SELECT * FROM business_card
    WHERE id='$id'");
    $num=mysql_num_rows($result);  //获取行数
    if($num>0){

                //修改数据库字段
                mysql_query("UPDATE business_card SET phone = '$phone'
                WHERE id = '$id'");
                mysql_query("UPDATE business_card SET mail = '$mail'
                WHERE id = '$id'");
                mysql_query("UPDATE business_card SET name = '$name'
                WHERE id = '$id'");
                mysql_query("UPDATE business_card SET sex = '$sex'
                WHERE id = '$id'");
                mysql_query("UPDATE business_card SET wx = '$wx'
                WHERE id = '$id'");
                mysql_query("UPDATE business_card SET region = '$region'
                WHERE id = '$id'");
                mysql_query("UPDATE business_card SET position = '$position'
                WHERE id = '$id'");
                mysql_query("UPDATE business_card SET geology = '$geology'
                WHERE id = '$id'");
                mysql_query("UPDATE business_card SET detail = '$detail'
                WHERE id = '$id'");
    }else{
        //插入数据到数据库 
        $strsql = "insert into business_card (nickname,head,phone,mail,name,sex,wx,region,position,geology,detail,id,now_time) values('$nickname','$head','$phone','$mail','$name','$sex','$wx','$region','$position','$geology','$detail','$id','$now_time')";
        $result = @mysql_query($strsql);

    }
     echo $num;




}else{
//提交图片
    $now_time = $_POST['now_time'];
    $img = $_FILES['file']['name'];
    $q = "SELECT * FROM business_card"; //SQL查询语句 SELECT * FROM 表名
    $rs = mysql_query($q); //获取数据集
    while($row=mysql_fetch_array($rs)){
        $result = @mysql_query($strsql);
            if($row["now_time"]==$now_time){
                if($row["img"]!=""){
                $ab =$row["img"].','.$img;
                }else{
                $ab =$img;
                }
                //修改数据库字段
                mysql_query("UPDATE business_card SET img = '$ab'
                WHERE now_time = '$now_time'");
                echo urldecode(json_encode($ab));
            }
    }

    move_uploaded_file($_FILES["file"]["tmp_name"],"upload/" . $_FILES["file"]["name"]); 
}