CODEWITHSUNDEEP
phpandroidmysqlpdomysqli
Alex Lungu
Alex Lungu

Reputation: 1114

Why does my mysql query always return an empty result?

I'm trying to read one row from my database table "cond" using the ID of the row. In this case I only have one row with the ID=1. The problem is that this code always returns that $result is empty. I've been trying to fix it for a long time and I tried to do it with PDO or mysqli too but my knowledge of coding is really limited. How can I get the read the row properly?

This is my php code: 

$response = array();
require_once __DIR__ . '/db_connect.php';
$db = new DB_CONNECT();    
if (isset($_GET["pid"])) {
$pid = $_GET['pid'];
$result = mysql_query("SELECT *FROM cond WHERE id = $pid");

if (!empty($result)) {
    if (mysql_num_rows($result) > 0) {

        $result = mysql_fetch_array($result);

        $product = array();
        $product["id"] = $result["id"];
        $product["name"] = $result["name"];
        $product["mon"] = $result["mon"];
        $product["tue"] = $result["tue"];
        $product["wed"] = $result["wed"];
        $product["thu"] = $result["thu"];
        $product["fri"] = $result["fri"];
        $product["sat"] = $result["sat"];
        $product["sun"] = $result["sun"];
        $product["version"]=$result["version"];

        // success
        $response["success"] = 1;

        // user node
        $response["product"] = array();

        array_push($response["product"], $product);

        // echoing JSON response
        echo json_encode($response);
    } else {
        // no product found
        $response["success"] = 0;
        $response["message"] = "No product found. Result=0";

        // echo no users JSON
        echo json_encode($response);
    }
} else {
    // no product found
    $response["success"] = 0;
    $response["message"] = "No product found.Result=empty";

    // echo no users JSON
    echo json_encode($response);
}
} else {
// required field is missing
$response["success"] = 0;
$response["message"] = "Required field(s) is missing";

// echoing JSON response
echo json_encode($response);
}
 ?>

And this is the java code: 

List<NameValuePair> params2 = new ArrayList<NameValuePair>();
params2.add(new BasicNameValuePair("pid", "1")); 
JSONObject json = jsonParser.makeHttpRequest(url_product_detials, "GET", params2);
Log.d("Single Product Details", json.toString());

Thanks!

Edit: Using suggested PDO

After being suggested to use PDO I uploaded the next code: 

<?php

$id=$_POST["pid"];


try {
require_once 'conf.php';
$conn = mysqlConnector();
$stmt = $conn->prepare('SELECT * FROM cond WHERE id = :id');
$stmt->execute(array('id' => $id));
$result = $stmt->fetchAll();

if ( count($result) ) { 
foreach($result as $row) {
     echo json_encode($result);

}} else {
echo "No rows returned.";
}
} catch(PDOException $e) {
echo 'ERROR: ' . $e->getMessage();
}
?>

But now I get this error:

Error parsing data org.json.JSONException: End of input at character 0 of 
threadid=12: thread exiting with uncaught exception (group=0x40cd7930)
FATAL EXCEPTION: AsyncTask #1
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:299)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
at java.util.concurrent.FutureTask.run(FutureTask.java:239)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
at java.lang.Thread.run(Thread.java:856)
 Caused by: java.lang.NullPointerException
at com.goout.ListClubs$GetProductDetails.doInBackground(ListClubs.java:456)
at com.goout.ListClubs$GetProductDetails.doInBackground(ListClubs.java:1)
at android.os.AsyncTask$2.call(AsyncTask.java:287)
at java.util.concurrent.FutureTask.run(FutureTask.java:234)
... 4 more
  Activity com.goout.ListClubs has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{410fb410 V.E..... R......D 0,0-480,144} that was originally added here
   android.view.WindowLeaked: Activity com.goout.ListClubs has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{410fb410 V.E..... R......D 0,0-480,144} that was originally added here
at android.view.ViewRootImpl.<init>(ViewRootImpl.java:354)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:216)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
at android.app.Dialog.show(Dialog.java:281)
at com.goout.ListClubs$GetProductDetails.onPreExecute(ListClubs.java:435)
at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
at android.os.AsyncTask.execute(AsyncTask.java:534)
at com.goout.ListClubs.onCreate(ListClubs.java:87)
at android.app.Activity.performCreate(Activity.java:5104)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2262)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358)
at android.app.ActivityThread.access$600(ActivityThread.java:153)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5227)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
at dalvik.system.NativeStart.main(Native Method)

So I guess the php code is wrong?

Upvotes: 1

Views: 3186

Answers (2)

Sujit Poudel
Sujit Poudel

Reputation: 541

You said you database name is cond. Then what is your table name in the database? mysql_* is deprecated. Try the following

$mysqli = new mysqli("localhost", "username", "password", "cond");

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

if ($result = $mysqli->query("SELECT *FROM table_name WHERE id = $pid")) {

    /* determine number of rows result set */
    $row_cnt = $result->num_rows;

    if ($row_cnt>0)
    {
      while ($row = $result->fetch_row()) 
      {
        $product = array();
        $product["id"] = $result["id"];
        $product["name"] = $result["name"];
        $product["mon"] = $result["mon"];
        $product["tue"] = $result["tue"];
        $product["wed"] = $result["wed"];
        $product["thu"] = $result["thu"];
        $product["fri"] = $result["fri"];
        $product["sat"] = $result["sat"];
        $product["sun"] = $result["sun"];
        $product["version"]=$result["version"];

        // success
        $response["success"] = 1;

        // user node
        $response["product"] = array();

        array_push($response["product"], $product);

        // echoing JSON response
        echo json_encode($response); 
     }
    }
    else
    {
      // no product found
      $response["success"] = 0;
      $response["message"] = "No product found. Result=0";

      // echo no users JSON
      echo json_encode($response);
      /* close result set */
    }
    $result->close();
}

From http://php.net/manual/en/mysqli-result.num-rows.php

Upvotes: 0

Your Common Sense
Your Common Sense

Reputation: 157877

An empty response means there was error in the query.

Mysql won't tell you what was the error unless asked explicitly. So, you have to always check the result of every mysql function interacting with server and if result is FALSE - check mysql_error().

Also, you are using outdated mysql library. Quit it and start using PDO, which has built-tin error reporting.

Upvotes: 2

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