How to get data from a MySQL database in PHP?

Question

This is the php script I have written to get the data from a MySQL database but it gives the error mentioned later and also the app where I am using this script gives a timeouterror .

PHP Script:

<?php 

 define('HOST','***');
 define('USER','***');
 define('PASS','***');
 define('DB','champion_trial_database');


 $con = mysqli_connect('HOST', 'USER', 'PASS', 'DB');

 $sql ="SELECT * FROM `trial`";

 $r = mysqli_query($con,$sql);

 $res = mysqli_fetch_array($r);

 echo ("name:"+$res);

 mysqli_close($con);

 ?>

Main_activity.java file where a GET request is generated using the volley library is as follows:

import android.app.ProgressDialog;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;


public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private EditText editTextId;
    private Button buttonGet;
    private TextView textViewResult;

    private ProgressDialog loading;

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

        editTextId = (EditText) findViewById(R.id.editTextId);
        buttonGet = (Button) findViewById(R.id.buttonGet);
        textViewResult = (TextView) findViewById(R.id.textViewResult);

        buttonGet.setOnClickListener(this);
    }

    private void getData() {
        String id = editTextId.getText().toString().trim();
        if (id.equals("")) {
            Toast.makeText(this, "Please enter an id", Toast.LENGTH_LONG).show();
            return;
        }
        loading = ProgressDialog.show(this,"Please wait...","Fetching...",false,false);
        String url = "http://www.champion6346.5gbfree.com/getData.php";
        RequestQueue requestQueue = Volley.newRequestQueue(this);
        StringRequest stringRequest = new StringRequest(Request.Method.GET,url,

                new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                loading.dismiss();
                textViewResult.setText("Name: "+response);
               // showJSON(response);
            }
        },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Toast.makeText(MainActivity.this,error.getMessage(),Toast.LENGTH_LONG).show();
                        Log.d("TAG:","Error mode entered  ");
                        error.printStackTrace();
                    }
                });
        requestQueue.add(stringRequest);
    }
    @Override
    public void onClick(View v) {
        getData();
    }
}

This the error log of the server when I try to run the php script mentioned above:

[13-Apr-2017 13:43:50 America/Denver] PHP Warning:  mysqli_connect(): php_network_getaddresses: getaddrinfo failed: Name or service not known in /home/champion6346/public_html/getData.php on line 9
[13-Apr-2017 13:43:50 America/Denver] PHP Warning:  mysqli_connect(): (HY000/2002): php_network_getaddresses: getaddrinfo failed: Name or service not known in /home/champion6346/public_html/getData.php on line 9
[13-Apr-2017 13:43:50 America/Denver] PHP Warning:  mysql_query(): Access denied for user ''@'localhost' (using password: NO) in /home/champion6346/public_html/getData.php on line 14
[13-Apr-2017 13:43:50 America/Denver] PHP Warning:  mysql_query(): A link to the server could not be established in /home/champion6346/public_html/getData.php on line 14
[13-Apr-2017 13:43:50 America/Denver] PHP Warning:  mysql_fetch_array() expects parameter 1 to be resource, boolean given in /home/champion6346/public_html/getData.php on line 16
[13-Apr-2017 13:43:50 America/Denver] PHP Warning:  mysql_close() expects parameter 1 to be resource, boolean given in /home/champion6346/public_html/getData.php on line 20

Answer 1

In this situation I'd also get sure the db hostname indeed resolves to some ip address (e.g. ping the hostname or use dig/nslookup tools). If the hostname does not resolve this is the exact problem. Otherwise I'd trace code or use a network sniffer (wireshark, tdpdump, etc) to get sure if the PHP code understands your demand and indeed connects to the hostname you've specified. Can't comment due to low rating, thus answering.

Answer 2

Here are some fixes applied to your php code

<?php 

 define('HOST','****');
 define('USER','****');
 define('PASS','****');
 define('DB','champion_trial_database');


 $con = mysqli_connect(HOST, USER, PASS, DB);

 $sql ="SELECT * FROM trial";

 $r = mysqli_query($con,$sql);

 while ($row = mysqli_fetch_array($r, MYSQLI_ASSOC)) {
 echo "name:".$row['columnname'];
}

 mysqli_close($con);

 ?>

columnname is the name of the column, you look for values. You should adjust it.

UPDATE

You also have a connection problem, to solve it this answer might help https://stackoverflow.com/a/35608572

After you solved connection problem, code above should do what you need.