Using Jquery DataGrid with PHP and MySql as a Datagrid Part 2

Jquery Datatables has lots of options that allows fine control over the display of the table. The options can be provided as parameters at the time of initialization. Some of the options are

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01 02 03 04 05 06 07 08 09 10 11	<script type="text/javascript"> $(document).ready(function(e) {     $('.data-grid').dataTable(      {           "paging":   false,           "ordering": false,           "info":     false      }); }); </script>

<script type="text/javascript">
$(document).ready(function(e) {
    $('.data-grid').dataTable(
     {
          "paging":   false,
          "ordering": false,
          "info":     false

     });
});
</script> 

To change the number of records displayed in a table, change the "pageLength" option. For example 

"pageLength": 50 

A full list of options is available at https://datatables.net/reference/option/ 

Using Jquery DataGrid with PHP and MySql as a Datagrid Part 1

Datagrid is a major requirement in any Database application. Not many free datagrids are available for PHP. Those that are available lack in features. In this series we are going to use Jquery DataTable along with PHP and MySql to create a Sortable, Filterable, Customizable datagrid.

 Simple MySql Recordset Display

Step 1: First Lets Add All the Required Libraries to the Page. 

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1 2 3	<script src="https://code.jquery.com/jquery-1.12.4.js" type="text/javascript"></script> <script src="https://cdn.datatables.net/1.10.15/js/jquery.dataTables.min.js"></script> <link href="https://cdn.datatables.net/1.10.15/css/jquery.dataTables.min.css" rel="stylesheet" />

<script src="https://code.jquery.com/jquery-1.12.4.js" type="text/javascript"></script>
<script src="https://cdn.datatables.net/1.10.15/js/jquery.dataTables.min.js"></script>
<link href="https://cdn.datatables.net/1.10.15/css/jquery.dataTables.min.css" rel="stylesheet" />

Step 2: Get the data from the database and display it in an Html Table

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1 2 3	<table class="data-grid"> <thead> <tr>

<table class="data-grid">
<thead>
<tr>

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01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39	<?php // Define Database Connection Information define("HOSTNAME","localhost"); define("USERNAME","root"); define("PASS",""); define("DB","world"); // Make a Connection $connection=new mysqli(HOSTNAME,USERNAME,PASS,DB); if(!$connection){ echo "Sorry No Connection"; exit;   } // Get Column Names of the Table $results=$connection->query("SHOW COLUMNS from city"); // Print the Table while($headers=mysqli_fetch_array($results,MYSQLI_NUM)){ echo "<th>".$headers[0]."</th>"; } echo "</tr>"; echo "</thead><tbody>"; // Get Table Data from Database $output=$connection->query("SELECT * from city"); //Output the Data while($rs=mysqli_fetch_array($output,MYSQLI_NUM)){ echo "<tr>"; for($i=0;$i<count($rs);$i++){     echo "<td>".$rs[$i]."</td>"; } echo "</tr>"; } ?> </tbody> </tr> </table>

<?php
// Define Database Connection Information
define("HOSTNAME","localhost");
define("USERNAME","root");
define("PASS","");
define("DB","world");

// Make a Connection
$connection=new mysqli(HOSTNAME,USERNAME,PASS,DB);

if(!$connection){
echo "Sorry No Connection";
exit;   
}
// Get Column Names of the Table
$results=$connection->query("SHOW COLUMNS from city");
// Print the Table
while($headers=mysqli_fetch_array($results,MYSQLI_NUM)){
echo "<th>".$headers[0]."</th>";

}
echo "</tr>";
echo "</thead><tbody>";
// Get Table Data from Database
$output=$connection->query("SELECT * from city");

//Output the Data
while($rs=mysqli_fetch_array($output,MYSQLI_NUM)){
echo "<tr>";

for($i=0;$i<count($rs);$i++){
    echo "<td>".$rs[$i]."</td>";
}
echo "</tr>";
}
?>
</tbody>
</tr>
</table>

Step 3: Finally initialize the datatable .

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1 2 3 4 5	<script type="text/javascript"> $(document).ready(function(e) {     $('.data-grid').dataTable(); }); </script>

<script type="text/javascript">
$(document).ready(function(e) {
    $('.data-grid').dataTable();
});
</script>

Save the File in your virtual directory. Load it in your browser and you should see

The Source File can be downloaded from here.


In the next installment we will look into loading data into the Table using Ajax.

Hadoop MapReduce

MapReduce is a core component of the Apache Hadoop software framework. The MapReduce components as the name implies Maps and Reduces. It distributes work to different nodes within a cluster/map (MAP) and organize the returned result into a result of the query being made (REDUCE).


There are three main components of MapReduce

1. JobTracker: The node that manages all jobs in a cluster. It is also known as the master node. Jobs are divided into Tasks assigned to individual machines in a cluster. 
2. TaskTracker: A component that takes tracks every task assigned to an individual machine.
3. JobHistoryServer: This component tracks completed jobs.

MapReduce distributes input data and collate Results. It does so by operating in parallel across massive clusters. Jobs can be split across any number of servers. MapReduce is available in several languages. MapReduce libraries abstract Programmers from under the hood, and create task between having to worry about the intricacies of distributed computing paradigm.

Each node reports back to the master node. The master node can re-assign the task to any other node, if the child node doesn't report back. This makes MapReduce highly fault-tolerant, with the only single point of failure being the master node.

What is Hadoop

Hadoop is a framework to process huge amount of data across clusters of computers, using commodity hardware in a distributed computing environment. It can work on a single server or thousands of machines having their own storage. Hence it is a massively parallel execution environment that brings the power of supercomputing using only commodity hardware. Hadoop is primarily used for big data analytics. 
Hadoop should be classified as an ecosystem comprised of many components that range from data storage, to data integration, to data processing, to specialized tools for data analysts.

Hadoop Components

HDFS is a main component of Hadoop. It is a distributed File System able to run on commodity hardware. This is where the data is stored. It provides the foundation for other tools, such as HBase.

1. MapReduce: Hadoop’s main execution framework is MapReduce, a programming model for distributed, parallel data processing, breaking jobs into mapping phases and reduce phases (thus the name). MapReduce is a core component of the Apache Hadoop software framework. Hadoop enables resilient, distributed processing of massive unstructured data sets across commodity computer clusters, in which each node of the cluster includes its own storage.
2. HBase: A column-oriented NoSQL database. Simply put HBase is the DataStore for Hadoop and BigData. 
3. Zookeeper: It is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services. Zookeeper is Hadoop’s distributed coordination service. Specifically designed for distributed management. Many components of Hadoop depend on Zookeeper.
4. Oozie: Oozie is Hadoop workflow scheduler. It schedules Hadoop Jobs.It is integrated with rest of Hadoop stack.
5. Pig: Pig is a platform for analyzing large data sets. It consists of its own scripting language, PIG Latin which is translated by the compiler that produces MapReduce sequences.
6. Hive: An SQL-like, high-level language It works like pig but translate Sql like queries into MapReduce sequences.

The Hadoop ecosystem also contains several other frameworks

1. Sqoop: Tool to transfer data to and from Hadoop to relational databases. 
2. Flume: Tool to move data from individual machines to HDFS.

Alipur Ka Aili

Delegates in C#

Delegates in C#

So what are Delegates? And why do we need them. Delegates are basically pointers to functions (C, C++ parlance). Delegates are reference type variables holding reference to a method. 

First off lets write some code to demonstrate how Delegates are declared and used.

This is a basic example of Delegate. At line 7 we are declaring a delegate

public delegate int ADelegate(int num); 

 On line 10 we assign a method to this delegate

ADelegate md=SquareNum;

And then we call upon the method using the delegate reference.

Note: The delegate must have the same signature as the method that it is referencing.

We can reference another method by the same delegate without any problem. (The signature should be the same)

On line 12 we reference another method

md=CubeNum;

Use of Delegates in Events

Delegates are best exemplified by their use in events. For e.g on a Button Event we can call a method using the below code.

button1.Click+=BTN_CLICK_HANDLER; 

For eg:

button1.Click+=button1_click;

We can then define button1_click as

private void button1_click(object sender, EventArgs e)
{

}
 

Recovering Linux installation after Windows install

Most people make the mistake of installing Windows after Linux. Offcourse one of the main reason is that due to myriad issues in windows, users often have to re-install windows. Not so the case with Linux. However after windows is installed it overrides the boot-loader and your Linux is hidden. Many people resort to re-install Linux in such a situation.

Worry not, the following steps will show you how to recover your boot-loader and be able to access Linux once again.

First up, download the Linux Live CD, burn it on the CD or follow the instructions at http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-windows to create a bootable USB.

Boot your computer from the USB. Once in the Live version, open a terminal

Issue the Following Command

sudo fdisk -l 

Check the partition where Linux is installed. It would be the one where the Type "Linux" is written. Then issue the command

sudo mount /dev/sdaXX /mnt

where XX in the sda is the number where you found the word Linux in the fdisk command.

In the above example it would be 7

At this point your Linux installation is mounted at the location /mnt.

Now we need to install the Grub bootloader.

sudo grub-install --root-directory=/mnt /dev/sda to install grub.  

This will install grub.

Reboot your system. Remove the USB/CD. The system will boot directly into Linux.

After your linux is booted, open the terminal and issue the command

sudo update-grub 

Restart your system. You will now see the Grub Menu on system startup.