Set - 9

Question 1 :

How can increase the performance of MySQL select query?

Answer :

We can use LIMIT to stop MySql for further search in table after we have received our required no. of records, also we can use LEFT JOIN or RIGHT JOIN instead of full join in cases we have related data in two or more tables.


Question 2 :

How can we change the name of a column of a table?

Answer :

MySQL query to rename table: RENAME TABLE tbl_name TO new_tbl_name
or,
ALTER TABLE tableName CHANGE OldName newName.


Question 3 :

When you want to show some part of a text displayed on an HTML page in red font color? What different possibilities are there to do this? What are the advantages/disadvantages of these methods?

Answer :

There are 2 ways to show some part of a text in red:

1. Using HTML tag <font color="red">
2. Using HTML tag <span style="color: red">


Question 4 :

When viewing an HTML page in a Browser, the Browser often keeps this page in its cache. What can be possible advantages/disadvantages of page caching? How can you prevent caching of a certain page (please give several alternate solutions)?

Answer :

When you use the metatag in the header section at the beginning of an HTML Web page, the Web page may still be cached in the Temporary Internet Files folder. 

A page that Internet Explorer is browsing is not cached until half of the 64 KB buffer is filled. Usually, metatags are inserted in the header section of an HTML document, which appears at the beginning of the document. When the HTML code is parsed, it is read from top to bottom. When the metatag is read, Internet Explorer looks for the existence of the page in cache at that exact moment. If it is there, it is removed. To properly prevent the Web page from appearing in the cache, place another header section at the end of the HTML document.


Question 5 :

What are the different ways to login to a remote server? Explain the means, advantages and disadvantages? 

Answer :

There is at least 3 ways to logon to a remote server:
Use ssh or telnet if you concern with security
You can also use rlogin to logon to a remote server.


Question 6 :

Please give a regular expression (preferably Perl/PREG style), which can be used to identify the URL from within a HTML link tag.

Answer :

Try this: /href="([^"]*)"/i


Question 7 :

How can I use the COM components in php?

Answer :

The COM class provides a framework to integrate (D)COM components into your PHP scripts.
string COM::COM( string module_name [, string server_name [, int codepage]]) - COM class constructor.

Parameters:

module_name: name or class-id of the requested component.
server_name: name of the DCOM server from which the component should be fetched. If NULL, localhost is assumed. To allow DCOM com, allow_dcom has to be set to TRUE in php.ini.
codepage - specifies the codepage that is used to convert php-strings to unicode-strings and vice versa. Possible values are CP_ACP, CP_MACCP, CP_OEMCP, CP_SYMBOL, CP_THREAD_ACP, CP_UTF7 and CP_UTF8.
Usage:

$word->Visible = 1; //open an empty document 
$word->Documents->Add(); //do some weird stuff 
$word->Selection->TypeText("This is a test…"); 
$word->Documents[1]->SaveAs("Useless test.doc"); //closing word 
$word->Quit(); //free the object 
$word->Release(); 
$word = null;

 


Question 8 :

How many ways we can give the output to a browser?

Answer :

HTML output
PHP, ASP, JSP, Servlet Function
Script Language output Function
Different Type of embedded Package to output to a browser


Question 9 :

What is the default session time in php and how can I change it?

Answer :

The default session time in php is until closing of browser


Question 10 :

What changes I have to do in php.ini file for file uploading? 

Answer :

Make the following line uncomment like:
; Whether to allow HTTP file uploads.
file_uploads = On
; Temporary directory for HTTP uploaded files (will use system default if not
; specified).
upload_tmp_dir = C:\apache2triad\temp
; Maximum allowed size for uploaded files.
upload_max_filesize = 2M


Question 11 :

How can I set a cron and how can I execute it in Unix, Linux, and windows?

Answer :

Cron is very simply a Linux module that allows you to run commands at predetermined times or intervals. In Windows, it's called Scheduled Tasks. The name Cron is in fact derived from the same word from which we get the word chronology, which means order of time.
The easiest way to use crontab is via the crontab command.

# crontab

This command 'edits' the crontab. Upon employing this command, you will be able to enter the commands that you wish to run. My version of 
Linux uses the text editor vi. You can find information on using vi here.

The syntax of this file is very important – if you get it wrong, your crontab will not function properly. The syntax of the file should be as follows:
minutes hours day_of_month month day_of_week command

All the variables, with the exception of the command itself, are numerical constants. In addition to an asterisk (*), which is a wildcard that allows any value, the ranges permitted for each field are as follows:

Minutes: 0-59
Hours: 0-23
Day_of_month: 1-31
Month: 1-12
Weekday: 0-6

We can also include multiple values for each entry, simply by separating each value with a comma.
command can be any shell command and, as we will see momentarily, can also be used to execute a Web document such as a PHP file.
So, if we want to run a script every Tuesday morning at 8:15 AM, our mycronjob file will contain the following content on a single line:

15 8 * * 2 /path/to/scriptname

This all seems simple enough, right? Not so fast! If you try to run a PHP script in this manner, nothing will happen (barring very special configurations that have PHP compiled as an executable, as opposed to an Apache module). The reason is that, in order for PHP to be parsed, it needs to be passed through Apache. In other words, the page needs to be called via a browser or other means of retrieving 

Web content. For our purposes, I'll assume that your server configuration includes wget, as is the case with most default configurations. To test your configuration, log in to shell. If you're using an RPM-based system (e.g. Redhat or Mandrake), type the following:

# wget help

If you are greeted with a wget package identification, it is installed in your system.
You could execute the PHP by invoking wget on the URL to the page, like so:

# wget http://www.example.com/file.php

Now, let's go back to the mailstock.php file we created in the first part of this article. We saved it in our document root, so it should be accessible via the Internet. Remember that we wanted it to run at 4PM Eastern time, and send you your precious closing bell report? Since I'm located in the Eastern timezone, we can go ahead and set up our crontab to use 4:00, but if you live elsewhere, you might have to compensate for the time difference when setting this value.
This is what my crontab will look like:

0 4 * * 1,2,3,4,5 we get http://www.example.com/mailstock.php


Question 12 :

Steps for the payment gateway processing?

Answer :

An online payment gateway is the interface between your merchant account and your Web site. The online payment gateway allows you to immediately verify credit card transactions and authorize funds on a customer's credit card directly from your Web site. It then passes the transaction off to your merchant bank for processing, commonly referred to as transaction batching


Question 13 :

How many ways I can redirect a PHP page?

Answer :

Here are the possible ways of php page redirection.

1. Using Java script: 
'; echo 'window.location.href="'.$filename.'";'; echo ''; echo ''; echo ''; echo ''; } } redirect('http://maosjb.com'); ?>

2. Using php function: header("Location:http://maosjb.com ");


Question 14 :

List out different arguments in PHP header function?

Answer :

void header ( string string [, bool replace [, int http_response_code]])

 


Question 15 :

What type of headers have to be added in the mail function to attach a file?

Answer :

$boundary = '--' . md5( uniqid ( rand() ) );
$headers = "From: \"Me\"\n";
$headers .= "MIME-Version: 1.0\n";
$headers .= "Content-Type: multipart/mixed; boundary=\"$boundary\"";