现在我正在做预订申请。因此，我尝试将变量发送到php并提取与我发送的变量匹配的行。具体来说，将userbranch从androidstudio发送到php，并提取coursebranch与userbranch具有相同值的行。我使用where来设置条件，但它无法检索数据。
这是我的php代码（courselist.php）

<?php
header("Content-Type: text/html; charset=UTF-8");
$con = mysqli_connect($host, $username, $pwd, $db) or die('Unable to connect');
$courseBranch = $_GET["userBranch"]

if(mysqli_connect_error($con))
{
    echo "Failed to Connect to Database".mysqli_connect_error();
}

$sql = "SELECT courseID, courseTeacher, courseDay, courseTime, courseBranch  FROM COURSE WHERE courseBranch = '$courseBranch'";
$result = mysqli_query($con,$sql);
if ($result)
{
    while ($row = mysqli_fetch_array($result))
    {
        $flag[] = $row;
    }
    print(json_encode($flag));
}
mysqli_close($con);                        
?>

这是我的android studio代码，在这里解析数据

<?php
private int parseData(){
    try {
        JSONArray ja = new JSONArray(jsonData);
        JSONObject jo = null;

        courseTeacher.clear();
        courseDay.clear();
        courseTime.clear();
        courseTeacherParse.clear();

        for(int i = 0; i <ja.length();i++)
        {
            jo = ja.getJSONObject(i);
            int id = jo.getInt("courseID");
            String name = jo.getString("courseTeacher");
            String day = jo.getString("courseDay");
            String time = jo.getString("courseTime");
            String branch = jo.getString("courseBranch");

            course = new Course();
            course.setCourseTeacher(name);
            course.setCourseDay(day);
            course.setCourseTime(time);
            courseTeacher.add(name);
            courseDay.add(day);
            courseTime.add(time);
            courseBranch.add(branch);
        } catch (JSONException e) {
            e.printStackTrace();
        }
?>

这是地址

<?php
    String urlAddress = "";
    try {
        urlAddress = "http://show981111.cafe24.com/CourseList.php?userBranch=" + URLEncoder.encode(userBranch, "UTF-8");
    } catch (Exception e) {
        e.printStackTrace();
    }