Web Developers Portal

Tuesday 31 May 2022

How to reset AUTO_INCREMENT in MySQL

ALTER TABLE tablename AUTO_INCREMENT = 1

Friday 20 May 2022

DataTables warning: table id=example - Invalid JSON response: How to Debug?

Use CTRL+SHIFT+I (or navigate to Current Page Control > Developer > Developer Tools. In the newer versions of Chrome, click the Wrench icon > Tools > Developer Tools.) to enable the Developer Tools.
From within the developer tools click on the Network button.
Click the "XHR" sub-button.
Initiate an AJAX call.
Double click the Name of the page under the Network button. It will open a new page with the details of the error.

Wednesday 11 May 2022

Prevent caching data from database in PhP FullCalendar

Friday 6 May 2022

How to configure PHP Calendar with events from database?

Download fullcalendar file from : https://github.com/fullcalendar/fullcalendar/releases

PhP Page

Inside <HEAD> Tag

Inside BODY Tag

<body>
<div class="container">
<div class="row">
<div class="col-md-12">
<h1 align="center" style=" padding: 3%;"> Calendar Heading</h1>
<div id='calendar'></div>
</div>
</div>
</div>
</body>

loadevent.php

--> Database connection establishment

$data = array();
$stmt = $con->prepare(" SQL QUERY ");
$stmt->execute();
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()) {
$data[] = array(
'id' => $row["No"],
'title' => $row["title"], // DB ATTRIBUTE NAME FOR TITLE

'start' => $row["DATE1"], // DB START DATE ENTRY in yy-mm-dd 00:00:00 format
'end' => $row["DATE2"], // DB END DATE ENTRY in yy-mm-dd 00:00:00 format
'description' => $row[" Description "], // DB Description attribute

);
//result is in row
}

echo json_encode($data);

Tuesday 3 May 2022

Warning: mysqli_query() expects parameter 1 to be mysqli, resource given

Reason for the error:
You are mixing mysqli and mysql extensions in the code, which will not work. mysqli has many improvements over the original mysql extension, so it is recommended to use mysqli .

Friday 29 April 2022

Pre Populate jquery Token input textbox with PhP MySQLi Resultset

Tokeninput is a jQuery plugin that allows users to select multiple items from a predefined list.

Download jquery token input plugin from https://loopj.com/jquery-tokeninput/
Extract the zip file and put jquery.tokeninput.js and token-input.css in the application root folder.
Download the latest version of jquery.min.js

SQL

CREATE TABLE `user` (

`id` int(10) NOT NULL AUTO_INCREMENT,

`name` varchar(40) DEFAULT NULL,

`designation` varchar(50) DEFAULT NULL,

`email` varchar(40) DEFAULT NULL,

PRIMARY KEY (id)

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

INSERT INTO `user` (`id`, `name`, `designation`, `email`) VALUES

(1, 'User1', 'Senior Manager', 'user1@gm.com'),

(2, 'User2', 'Head of IT', 'aru@rrg.com');

PhP Code

<!DOCTYPE html>

<head>

<title>Token input Demo</title>

<link

href="https://fonts.googleapis.com/css?family=Lato:400,700,300|Open+Sans:400,300,600,700"

rel="stylesheet" />

</head>

<?php

error_reporting(0);

$con = mysqli_connect("localhost", "root", "", "rgcbres_accounts");

if (mysqli_connect_errno()) {

echo "Failed to connect to MySQL: " . mysqli_connect_error();

}

$(document).ready(function () {

$("#nameinput").tokenInput("tget-users.php", {

});

</script>

<body>

<h4>Token Input Demo</h4>

<form action="<?php echo $_SERVER['PHP_SELF'];?>" method="post"

id="searchform" enctype="multipart/form-data">

<label class="control-label col-sm-3" for="scst">Name <font

style="color: red;">*</font></label>

<input type="text" id="nameinput" name="nameinput" required=""

class="form-control" placeholder="" />

</div>

<input type="submit" class="btn btn-default" name="Submit"

value="Submit">

</div>

</form>

<?php

if ($_POST['Submit']) {

if (trim($_POST['nameinput']) != "") {

$selected_name_arr = array();

$selected_nameinput = $_POST['nameinput'];

$selected_name_arr = explode(',', $selected_nameinput);

<form class="form-horizontal" id="saveform" action="#" method="post"

enctype="multipart/form-data">

<thead>

<tr>

Designation </b></td>

<td style="background-color: #f0ad4e; width: 20%;"><b> Email </b></td>

</tr>

</thead>

<tbody>

<?php

$sql = "SELECT * FROM user WHERE id IN (" . implode(',', $selected_name_arr) . ")";

$result = $con->query($sql);

$sino = 1;

if ($result->num_rows > 0) {

// output data of each row

while ($row = $result->fetch_assoc()) {

<tr>

</tr>

<?php

$sino ++;

}

</tbody>

</table>

</div>

</form>

<?php

}

</div>

</body>

</html>

tget-users.php

<?php

$con = mysqli_connect("localhost", "root", "", "rgcbres_accounts");

if (mysqli_connect_errno()) {

echo "Failed to connect to MySQL: " . mysqli_connect_error();

}

$users_arr = array();

$searchTerm = $_GET['q'];

$query = $con->query("SELECT id,name FROM user WHERE name LIKE '".$searchTerm."%' ORDER BY name ASC LIMIT 15");

if($query->num_rows > 0){

while($row = $query->fetch_assoc()){

$users_arr[] = $row;

}

echo json_encode($users_arr);

Distributed Systems

Distributed Systems

Consists of multiple computers and software components that communicate through a computer network.
Can consist of any number of possible configurations, such as mainframes, workstations, personal computers, and so on.
The computers interact with each other and share the resources of the system to achieve a common goal

Advantages of Distributed Systems

Reliability (fault tolerance)

The important advantage of distributed computing system is reliability. If some of the machines within the system crash, the rest of the computers remain unaffected and work does not stop.

Scalability

In distributed computing the system can easily be expanded by adding more machines as needed.

Sharing of Resources

Shared data is essential to many applications such as banking, reservation system. As data or resources are shared in distributed system, other resources can be also shared (e.g. expensive printers).

Flexibility

As the system is very flexible, it is very easy to install, implement and debug new services.

Speed

A distributed computing system can have more computing power and it's speed makes it different than other systems.

Open system

As it is open system, every service is equally accessible to every client i.e. local or remote.

Performance

The collection of processors in the system can provide higher performance (and better price/performance ratio) than a centralized computer.

Disadvantages of Distributed Systems

Troubleshooting

Troubleshooting and diagnosing problems.

Software

Less software support is the main disadvantage of distributed computing system.

Networking

The network infrastructure can create several problems such as transmission problem, overloading, loss of messages.

Security

Easy access in distributed computing system increases the risk of security and sharing of data generates the problem of data security