Dimensional modeling is often used in Data warehousing. In simpler words it is a rational or consistent design technique used to build a data warehouse. DM uses facts and dimensions of a warehouse for its design. A snow and star flake schema represent data modeling.

Data mining is a method for comparing large amounts of data for the purpose of finding patterns. Data mining is normally used for models and forecasting. Data mining is the process of correlations, patterns by shifting through large data repositories using pattern recognition techniques.

Data warehousing is the central repository for the data of several business systems in an enterprise. Data from various resources extracted and organized in the data warehouse selectively for analysis and accessibility.

Data warehousing is a process of repository of electronic data of an organization. For the purpose of reporting and analysis, data warehousing is used. The essence concept of data warehousing is to provide data flow of architectural model from operational system to decision support environments. 

Copy() makes a copy of the file. It returns TRUE on success. It can copy from any source to destination. Move simply Moves the file to destination if the file is valid. While move can move the uploaded file from temp server location to any destination on the server. If filename is a valid upload file, but cannot be moved for some reason, no action will occur.

Opendir():- It opens the directory. This function returns a directory stream on success and FALSE and an error on failure.

Syntax:

Opendir(directory, context)

Context is a set of options that can modify the behavior of a stream

Example: opens sample directory.

$dir = opendir("directory");

Readdir(): It returns an entry from a directory handle opened by opendir().

Syntax:

Readdir(dir_stream)

Example:

$file = readdir($dir);

closedir(): It closes a directory handle opened by opendir().

Syntax:

closedir(dir_stream)

Example:

$file = close($dir);

Chmod() is used for changing permissions on a file.

Syntax:

Chmod(file, mode)

Mode here specifies the permissions as follows:

The first number is always zero

The second number specifies permissions for the owner

The third number specifies permissions for the owner's user group

The fourth number specifies permissions for everybody else

Possible values (to set multiple permissions, add up the following numbers)

1 = execute permissions

2 = write permissions

4 = read permissions

Example:

// everything for owner, read for owner's group

chmod("test.txt",0740);

User names and passwords in PHP can be encrypted using md5 function.

MD5 function calculates the md5 hash of a string. It is basically used for encryption. It is also used for digital signature applications, where a large file must be "compressed" in a secure manner.

Example:

Md5($str);

Crypt() function can also be used to encrypt a string,. It used MD5, DES or blow fish algorithms for encryption.

Syntax:

Crypt(str, salt)

Salt is an optional parameter used to increase the number of characters encoded, to make the encoding more secure

Following are the steps to create a simple AD rotator script without using database in PHP:

- All the ad’s can be collected in one place and be displayed randomly.rand() function can be used for this purpose.

- In order to NOT use any database, a flat file can be used to store the ad’s.

- In order to store the Ad’s information (HTML code), a flat file say “ad.txt” can be created.

- The random number can be stored in a variable 

$result_random=rand(1, 100);

- Conditions can be checked to display the ad’s.

if($result_random<=70)

{

      echo "Display ad1";

}