上传一个变量到sql查询

Question

In my app I want to fetch JSON data from a server. For that I want the user to enter a variable that goes into the fetching query, but the way I tried it my app doesn't get any response from the server:

<?php

$conn = new mysqli($servername, $username, $password, $dbname);

if(isset($_POST['name'])){
 $query = "INSERT INTO TestTable (name) VALUES ('$_POST[name]')";

 if(mysqli_query($conn,$query)){ 
     echo 'Data Submit Successfully';
 }else{
     echo 'Try Again';
 }    
}


$var = $_POST['name'];

 $query = "SELECT * FROM TestTable WHERE id = '$var'";

    $result = mysqli_query($conn, $query);

    while($row = mysqli_fetch_assoc($result)) {
        $array[] = $row;
    }


    header('Content-Type:Application/json');
    echo json_encode($array);
    mysqli_close($conn);

?>

The uploaded variable is posted into the table as it should do. And If I set $var to a fixed value I do get a correct response. But what do I have to change so that my posted Variable gets into the selecting query?

Edit: here is the code of my uploading the variable and fetching the result - the GetData() and the InsertData() methods are used to upload and the other two to fetch:

 public class MainActivity extends AppCompatActivity {

    List<GetDataAdapter> GetDataAdapter1;
    RecyclerView recyclerView;
    RecyclerView.LayoutManager recyclerViewlayoutManager;
    RecyclerView.Adapter recyclerViewadapter;
    ProgressBar progressBar;

    String ServerURL = "https://x.com/test.php";
    EditText name;
    Button button;
    String TempName;
    String JSON_ID = "id";
    String JSON_NAME = "name";

    JsonArrayRequest jsonArrayRequest;
    com.android.volley.RequestQueue requestQueue;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        GetDataAdapter1 = new ArrayList<>();
        recyclerView = (RecyclerView) findViewById(R.id.recyclerView1);
        progressBar = (ProgressBar) findViewById(R.id.progressBar1);
        button = (Button) findViewById(R.id.button);
        recyclerView.setHasFixedSize(true);
        recyclerViewlayoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(recyclerViewlayoutManager);
        name = (EditText) findViewById(R.id.editText);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                GetData();
                InsertData(TempName);
                JSON_DATA_WEB_CALL();
            }
        });
    }

    public void GetData() {
        TempName = name.getText().toString();
    }

    public void InsertData(final String a) {

        class SendPostReqAsyncTask extends AsyncTask<String, Void, String> {
            @Override
            protected String doInBackground(String... params) {

                String NameHolder = a;

                List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();

                nameValuePairs.add(new BasicNameValuePair("name", NameHolder));

                try {
                    HttpClient httpClient = new DefaultHttpClient();
                    HttpPost httpPost = new HttpPost(ServerURL);
                    httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
                    HttpResponse httpResponse = httpClient.execute(httpPost);
                    HttpEntity httpEntity = httpResponse.getEntity();


                    String responseStr = EntityUtils.toString(resEntity).trim();
                    Log.v("TAG 2", "Response: " +  responseStr);



                } catch (ClientProtocolException e) {

                } catch (IOException e) {

                }
                return "Data Inserted Successfully";
            }

            @Override
            protected void onPostExecute(String result) {

                super.onPostExecute(result);

                Toast.makeText(MainActivity.this, "Data Submit Successfully", Toast.LENGTH_LONG).show();

            }
        }

        SendPostReqAsyncTask sendPostReqAsyncTask = new SendPostReqAsyncTask();

        sendPostReqAsyncTask.execute(a);
    }

    public void JSON_DATA_WEB_CALL() {

        jsonArrayRequest = new JsonArrayRequest(ServerURL,

                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        progressBar.setVisibility(View.GONE);
                        JSON_PARSE_DATA_AFTER_WEBCALL(response);
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {

                    }
                });

        requestQueue = Volley.newRequestQueue(this);
        requestQueue.add(jsonArrayRequest);

    }

    public void JSON_PARSE_DATA_AFTER_WEBCALL(JSONArray array) {

        for (int i = 0; i < array.length(); i++) {

            GetDataAdapter GetDataAdapter2 = new GetDataAdapter();
            JSONObject json = null;
            try {
                json = array.getJSONObject(i);
                GetDataAdapter2.setId(json.getInt(JSON_ID));
                GetDataAdapter2.setName(json.getString(JSON_NAME));

            } catch (JSONException e) {

                e.printStackTrace();
            }
            GetDataAdapter1.add(GetDataAdapter2);
        }

        recyclerViewadapter = new RecyclerViewAdapter(GetDataAdapter1, this);
        recyclerView.setAdapter(recyclerViewadapter);
    }
}

Answer 1

I suggest defining your post variable

$postVar = $_POST['variable'];

Then you should probably sanitise it before putting it in your SQL string.

I would prefer to use Prepared Statements. You should read about them herehttps://www.w3schools.com/php/php_mysql_prepared_statements.asp and use them instead as it fits your case exactly

Edit: How did you determine that your SELECT query didn't execute?

Edit 2: So I tested out modified version of your code:

if(isset($_GET['name'])){
   $query = "INSERT INTO TestTable (name) VALUES ('$_GET[name]')";
   echo $query;
   echo "</br></br>";
}

$var = "$_GET[name]";
echo $var;
echo "</br></br>";

$query = "SELECT * FROM TestTable WHERE name = '$var'";
echo $query;

The output that this produced by going to fileName.php?name=getVariableCorrectlyPopulated is:

INSERT INTO TestTable (name) VALUES ('getVariableCorrectlyPopulated')

getVariableCorrectlyPopulated

SELECT * FROM TestTable WHERE name = 'getVariableCorrectlyPopulated'

As you can see that is with GET instead of POST but data is going in correctly, I suggest you do the same or similar when you first make your scripts.You can use XAMPP (for example) for Apache distribution and run your scripts locally.

Edit 3+4:

Tested and is working:

<?php
if(isset($_POST['name'])){
    $servername = "localhost";
    $username = "root";
    $password = "";
    $dbname = "test";
    $conn = new mysqli($servername, $username, $password, $dbname);

    $array=array();
    $postVar =  $_POST['name'];
    //DONT FORGET TO SANITIZE

    $query1 = "INSERT INTO TestTable (name) VALUES ('$postVar')";
    if(mysqli_query($conn,$query1, false)){
//        echo 'Data Submit Successfully';
    }else{
        echo 'Try Again';
    }

    $query2 = "SELECT * FROM TestTable WHERE name = '$postVar'";
    $result = mysqli_query($conn, $query2);
    while($row = mysqli_fetch_assoc($result)) {
        $array[] = $row['name'];
    }

    echo json_encode($array);
}
?>

Please keep in mind there are way better ways to do this... See Prepared Statements above

Edit 5: You should change your code to what I gave you in Edit 3+4 (and sanitise the post data as well) and edit your android code so that you handle the response from doInBackground method https://developer.android.com/reference/android/os/AsyncTask .