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)?
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.
What Are The Advantages And Disadvantages Of Cascade Style Sheets?
External Style Sheets
Advantages
Can control styles for multiple documents at once Classes can be created for use on multiple HTML element types in many documents Selector and grouping methods can be used to apply styles under complex contexts
Disadvantages
An extra download is required to import style information for each document The rendering of the document may be delayed until the external style sheet is loaded Becomes slightly unwieldy for small quantities of style definitions
Embedded Style Sheets
Advantages
Classes can be created for use on multiple tag types in the document Selector and grouping methods can be used to apply styles under complex contexts No additional downloads necessary to receive style information
Disadvantage
This method can not control styles for multiple documents at once
Inline Styles
Advantages
Useful for small quantities of style definitions Can override other style specification methods at the local level so only exceptions need to be listed in conjunction with other style methods
Disadvantages
Does not distance style information from content (a main goal of SGML/HTML) Can not control styles for multiple documents at once Author can not create or control classes of elements to control multiple element types within the document Selector grouping methods can not be used to create complex element addressing scenarios
What Are The Differences Between Mysql_fetch_array(), Mysql_fetch_object(), Mysql_fetch_row()?
mysql_fetch_array - Fetch a result row as an associative array and a numeric array.
mysql_fetch_object - Returns an object with properties that correspond to the fetched row and moves the internal data pointer ahead. Returns an object with properties that correspond to the fetched row, or FALSE if there are no more rows.
mysql_fetch_row() - Fetches one row of data from the result associated with the specified result identifier. The row is returned as an array. Each result column is stored in an array offset, starting at offset 0.
What Are The Features And Advantages Of Object Oriented Programming?
One of the main advantages of OO programming is its ease of modification; objects can easily be modified and added to a system there by reducing maintenance costs. OO programming is also considered to be better at modeling the real world than is procedural programming. It allows for more complicated and flexible interactions. OO systems are also easier for non-technical personnel to understand and easier for them to participate in the maintenance and enhancement of a system because it appeals to natural human cognition patterns. For some systems, an OO approach can speed development time since many objects are standard across systems and can be reused. Components that manage dates, shipping, shopping carts, etc. can be purchased and easily modified for a specific system.
What Are The Reasons For Selecting Lamp (linux, Apache, Mysql, Php) Instead Of Combination Of Other Software Programs, Servers And Operating Systems?
All of those are open source resource. Security of Linux is very more than windows. Apache is a better server that IIS both in functionality and security. Mysql is world most popular open source database. Php is more faster that asp or any other scripting language.
What Is Meant By Nl2br()?
nl2br() inserts a HTML tag
before all new line characters n in a string.
echo nl2br("god bless n you");
output:
god bless
you
What Are The Current Versions Of Apache, Php, And Mysql?
PHP: PHP 5.1.2
MySQL: MySQL 5.1
Apache: Apache 2.1
How Can We Encrypt And Decrypt A Data Presented In A Table Using Mysql?
You can use functions: AES_ENCRYPT() and AES_DECRYPT() like:
AES_ENCRYPT(str, key_str)
AES_DECRYPT(crypt_str, key_str)
How Can We Destroy The Cookie?
Set the cookie with a past expiration time.
How Can I Retrieve Values From One Database Server And Store Them In Other Database Server Using Php?
For this purpose, you can first read the data from one server into session variables. Then connect to other server and simply insert the data into the database.
How Can We Submit From Without A Submit Button?
Trigger the JavaScript code on any event ( like onSelect of drop down list box, onfocus, etc ) document. myform.submit(); This will submit the form.
If We Login More Than One Browser Windows At The Same Time With Same User And After That We Close One Window, Then Is The Session Is Exist To Other Windows Or Not? And If Yes Then Why? If No Then Why?
Session depends on browser. If browser is closed then session is lost. The session data will be deleted after session time out. If connection is lost and you recreate connection, then session will continue in the browser.
What's The Difference Between Accessing A Class Method Via -> And Via ::?
:: is allowed to access methods that can perform static operations, i.e. those, which do not require object initialization.
What Are The Mysql Database Files Stored In System ?
Data is stored in name.myd
Table structure is stored in name.frm
Index is stored in name.myi
Explain Normalization Concept?
The normalization process involves getting our data to conform to three progressive normal forms, and a higher level of normalization cannot be achieved until the previous levels have been achieved (there are actually five normal forms, but the last two are mainly academic and will not be discussed).
First Normal Form
The First Normal Form (or 1NF) involves removal of redundant data from horizontal rows. We want to ensure that there is no duplication of data in a given row, and that every column stores the least amount of information possible (making the field atomic).
Second Normal Form
Where the First Normal Form deals with redundancy of data across a horizontal row, Second Normal Form (or 2NF) deals with redundancy of data in vertical columns. As stated earlier, the normal forms are progressive, so to achieve Second Normal Form, your tables must already be in First Normal Form.
Third Normal Form
I have a confession to make; I do not often use Third Normal Form. In Third Normal Form we are looking for data in our tables that is not fully dependant on the primary key, but dependant on another value in the table
What Is The Difference Between Php4 And Php5?
PHP4 cannot support oops concepts and Zend engine 1 is used.
PHP5 supports oops concepts and Zend engine 2 is used.
Error supporting is increased in PHP5.
XML and SQLLite will is increased in PHP5.
What Are The Advantages Of Stored Procedures, Triggers, Indexes?
A stored procedure is a set of SQL commands that can be compiled and stored in the server. Once this has been done, clients don't need to keep re-issuing the entire query but can refer to the stored procedure. This provides better overall performance because the query has to be parsed only once, and less information needs to be sent between the server and the client. You can also raise the conceptual level by having libraries of functions in the server. However, stored procedures of course do increase the load on the database server system, as more of the work is done on the server side and less on the client (application) side. Triggers will also be implemented. A trigger is effectively a type of stored procedure, one that is invoked when a particular event occurs. For example, you can install a stored procedure that is triggered each time a record is deleted from a transaction table and that stored procedure automatically deletes the corresponding customer from a customer table when all his transactions are deleted.
Indexes are used to find rows with specific column values quickly. Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. The larger the table, the more this costs. If the table has an index for the columns in question, MySQL can quickly determine the position to seek to in the middle of the data file without having to look at all the data. If a table has 1,000 rows, this is at least 100 times faster than reading sequentially. If you need to access most of the rows, it is faster to read sequentially, because this minimizes disk seeks.
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.
What Are The Advantages And Disadvantages Of Cascade Style Sheets?
External Style Sheets
Advantages
Can control styles for multiple documents at once Classes can be created for use on multiple HTML element types in many documents Selector and grouping methods can be used to apply styles under complex contexts
Disadvantages
An extra download is required to import style information for each document The rendering of the document may be delayed until the external style sheet is loaded Becomes slightly unwieldy for small quantities of style definitions
Embedded Style Sheets
Advantages
Classes can be created for use on multiple tag types in the document Selector and grouping methods can be used to apply styles under complex contexts No additional downloads necessary to receive style information
Disadvantage
This method can not control styles for multiple documents at once
Inline Styles
Advantages
Useful for small quantities of style definitions Can override other style specification methods at the local level so only exceptions need to be listed in conjunction with other style methods
Disadvantages
Does not distance style information from content (a main goal of SGML/HTML) Can not control styles for multiple documents at once Author can not create or control classes of elements to control multiple element types within the document Selector grouping methods can not be used to create complex element addressing scenarios
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What Are The Differences Between Mysql_fetch_array(), Mysql_fetch_object(), Mysql_fetch_row()?
mysql_fetch_array - Fetch a result row as an associative array and a numeric array.
mysql_fetch_object - Returns an object with properties that correspond to the fetched row and moves the internal data pointer ahead. Returns an object with properties that correspond to the fetched row, or FALSE if there are no more rows.
mysql_fetch_row() - Fetches one row of data from the result associated with the specified result identifier. The row is returned as an array. Each result column is stored in an array offset, starting at offset 0.
What Are The Features And Advantages Of Object Oriented Programming?
One of the main advantages of OO programming is its ease of modification; objects can easily be modified and added to a system there by reducing maintenance costs. OO programming is also considered to be better at modeling the real world than is procedural programming. It allows for more complicated and flexible interactions. OO systems are also easier for non-technical personnel to understand and easier for them to participate in the maintenance and enhancement of a system because it appeals to natural human cognition patterns. For some systems, an OO approach can speed development time since many objects are standard across systems and can be reused. Components that manage dates, shipping, shopping carts, etc. can be purchased and easily modified for a specific system.
What Are The Reasons For Selecting Lamp (linux, Apache, Mysql, Php) Instead Of Combination Of Other Software Programs, Servers And Operating Systems?
All of those are open source resource. Security of Linux is very more than windows. Apache is a better server that IIS both in functionality and security. Mysql is world most popular open source database. Php is more faster that asp or any other scripting language.
What Is Meant By Nl2br()?
nl2br() inserts a HTML tag
before all new line characters n in a string.
echo nl2br("god bless n you");
output:
god bless
you
What Are The Current Versions Of Apache, Php, And Mysql?
PHP: PHP 5.1.2
MySQL: MySQL 5.1
Apache: Apache 2.1
How Can We Encrypt And Decrypt A Data Presented In A Table Using Mysql?
You can use functions: AES_ENCRYPT() and AES_DECRYPT() like:
AES_ENCRYPT(str, key_str)
AES_DECRYPT(crypt_str, key_str)
How Can We Destroy The Cookie?
Set the cookie with a past expiration time.
How Can I Retrieve Values From One Database Server And Store Them In Other Database Server Using Php?
For this purpose, you can first read the data from one server into session variables. Then connect to other server and simply insert the data into the database.
How Can We Submit From Without A Submit Button?
Trigger the JavaScript code on any event ( like onSelect of drop down list box, onfocus, etc ) document. myform.submit(); This will submit the form.
If We Login More Than One Browser Windows At The Same Time With Same User And After That We Close One Window, Then Is The Session Is Exist To Other Windows Or Not? And If Yes Then Why? If No Then Why?
Session depends on browser. If browser is closed then session is lost. The session data will be deleted after session time out. If connection is lost and you recreate connection, then session will continue in the browser.
What's The Difference Between Accessing A Class Method Via -> And Via ::?
:: is allowed to access methods that can perform static operations, i.e. those, which do not require object initialization.
What Are The Mysql Database Files Stored In System ?
Data is stored in name.myd
Table structure is stored in name.frm
Index is stored in name.myi
Explain Normalization Concept?
The normalization process involves getting our data to conform to three progressive normal forms, and a higher level of normalization cannot be achieved until the previous levels have been achieved (there are actually five normal forms, but the last two are mainly academic and will not be discussed).
First Normal Form
The First Normal Form (or 1NF) involves removal of redundant data from horizontal rows. We want to ensure that there is no duplication of data in a given row, and that every column stores the least amount of information possible (making the field atomic).
Second Normal Form
Where the First Normal Form deals with redundancy of data across a horizontal row, Second Normal Form (or 2NF) deals with redundancy of data in vertical columns. As stated earlier, the normal forms are progressive, so to achieve Second Normal Form, your tables must already be in First Normal Form.
Third Normal Form
I have a confession to make; I do not often use Third Normal Form. In Third Normal Form we are looking for data in our tables that is not fully dependant on the primary key, but dependant on another value in the table
What Is The Difference Between Php4 And Php5?
PHP4 cannot support oops concepts and Zend engine 1 is used.
PHP5 supports oops concepts and Zend engine 2 is used.
Error supporting is increased in PHP5.
XML and SQLLite will is increased in PHP5.
What Are The Advantages Of Stored Procedures, Triggers, Indexes?
A stored procedure is a set of SQL commands that can be compiled and stored in the server. Once this has been done, clients don't need to keep re-issuing the entire query but can refer to the stored procedure. This provides better overall performance because the query has to be parsed only once, and less information needs to be sent between the server and the client. You can also raise the conceptual level by having libraries of functions in the server. However, stored procedures of course do increase the load on the database server system, as more of the work is done on the server side and less on the client (application) side. Triggers will also be implemented. A trigger is effectively a type of stored procedure, one that is invoked when a particular event occurs. For example, you can install a stored procedure that is triggered each time a record is deleted from a transaction table and that stored procedure automatically deletes the corresponding customer from a customer table when all his transactions are deleted.
Indexes are used to find rows with specific column values quickly. Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. The larger the table, the more this costs. If the table has an index for the columns in question, MySQL can quickly determine the position to seek to in the middle of the data file without having to look at all the data. If a table has 1,000 rows, this is at least 100 times faster than reading sequentially. If you need to access most of the rows, it is faster to read sequentially, because this minimizes disk seeks.
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