Database Programming

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B-Tree is an indexing technique most commonly used in databases and file systems where pointers to data are placed in a balance tree structure so that all references to any data can be accessed in an equal time frame. It is also a tree data structure which keeps data sorted so that searching, inserting and deleting can be done in logarithmic amortized time.

The B-Tree belongs to a group of techniques in computer science known as self-balancing search trees which attempts to automatically keep the number of levels of nodes under the root small at all times. It is the most preferred way to implement sets, associative arrays and other data structures that are used in computer programming languages, relational database management systems and low level data manipulations.

In the B-Tree, the records are stored in the leaves. This is the location where there is nothing more beyond it. The order of the tree determines the maximum number of children per node. Depth refers to the number of required disk access. A B-Tree can have up to millions and billions of records although it is not all the time that leaves necessarily contain a record but more than half certainly do.

When decision points on the tree, which are called nodes, are on the hard disk instead of on random access memory (RAM), B-Tree is the preferred technique as hard disks could work a thousand times slower compared to RAM because processes on hard disks requires mechanical parts. On RAM, processes are done purely in electronic media.

The nodes in a B-Tree can have a variable number of child nodes within a range pre-defined by the system. When a data is inserted or removed from a node, the number of child nodes also changes but the pre-defined ranged should be maintained so internal nodes may either be split or joined.

B-trees do not need frequent re-balancing as both the upper and lower bounds on the number of child nodes are typically fixed. As an example, a 2-3 B-Tree implementation has internal nodes that can only have 2 or 3 child nodes.

To keep the B-tree well balanced, all leaf nodes are required to be of the same depth. The depth only increases very slowly and infrequently.

Searching in a B-Tree structure starts from the root and traversed from top to bottom. Insertion is done by looking for a node where a new leaf or element should be. If there is still room or the maximum legal number of elements is not exceeded, insertion takes place. Otherwise, the leaf node splits into another tow nodes. Deletion in a B-Tree has two strategies. The first involves locating the item to be deleted and immediately doing the action then restructuring the tree. The second involves doing a traversing down the tree and laying out the restructure before deleting.

In a file system, a file may contain any number of B-Trees and each B-Tree must have a unique name composed of any string of characters. Each B-Tree names is saved in the file an item containing the number of the rood node of the B-Tree. Searching, inserting and deleting through the B-Tree starts from the root node.

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One advantage to end-user computing in retail business is more revenues. When users are able to find exactly what they want online, they will shop more from the comfort of their home.

It lets you write documents.

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explain the characteristic of database?

Text String

You don't have to bother with positioning in the file.

3124588707.84 Bytes equals 2.91 gigabytes

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They are stored on a hard drive or some other permanent storage device. The database application stores a table that identifies related files.

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A database is a collection of data. A database management system controls how those data are collected, stored and retrieved.

Actually it depends on how the shopper wants to install it for making it easier and manageful.

it contains a small amount of memory, or RAM, enough to configuration or setup information about the computer. This chip is responsible for remembering the current date and time, which hard drives and floppy drives are present, how the serial and parallel are configured and so forth. When the computer is first turned on, it looks to this CMOS chip to find out what hardware it should expect to find.

root@ernie:~# units 2438 units, 71 prefixes, 32 nonlinear units You have: minute/MB You want: Definition: 7.5e-06 s / bit

To uniquely identify a row in the table (i.e., no duplicates allowed)

There is no difference if you save simply all the data either in Database or List of tables in a excel sheet. But one advantage of storing all the data in the database is, any DBMS software can easily (of course it can take it from Excel sheet too) extract the data using SQL and it can easily provide the following functionality

1. Consistency of the Database

2. Durablily

3. Automicity

4. Isolate transaction execution

5. Data Security By giveing proper authorization.

But those things will be missed if you simply store the data in a Excell sheet or list. Those things should be taken care by a programmer by their code.

The main purpose of database is to mange the large bodies of information.Database is used to store interrelated data

e.g. Student information

1.Sparse matrix representation 2. polynomial manipulation 3.dyanamic memory storage 4.in symbol table

One is weighted, the other is not. Simple as.

One can always declare a datatype as static which will limit the scope to the file only. this way data hiding can be achived. For more clearance on the same please refer 'the C programming language'.

Data hiding means only relevant data is visible to the user and all the background information is hidden from the user. In c++, the variables are named as data members and these can be hidden with the help of private access specifier.

In procedural languages, variables(global variables) are free to flow from functions to functions and hence they were not secured. But in C++, only the class in which the data members are being declared can access them by using private specifier. As, the data members and also member functions of a class cannot be accessed outside the class if they have private access so, they get hidden from the user and hence the data hiding is achieved.

Also in inheritance when we derive a class from the base class then the derived class cannot access the private members of the base class. In addition, if a class is derived from another class privately i.e. for example syntax : class B : private A , is used then all the public and protected members (not private) becomes private to class B and cannot be accessed outside the class B, even by using the object of class B.

Hence, data hiding is achieved in C++ through private access specifier.

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Briefly, file processing is the act of creating, storing, managing and readingfiles containing data on your computer. File processing allows you to create a new file, for example, a written document, a picture or a poster. In order to create a new file, you must put data into a blank file and save it. File processing allows you to open files that you have already created and stored on your computer, in order to read through them. However, file processing usually does not allow you to edit content within the files, as thefiles are opened on a read only basis.

On the other hand, database management is a piece of software which allows you to create and maintain a collection of digital data on your computer, otherwise known as a database. Database management software is commonly used in large scale businesses and organizations, where thedatabase administrators are granted a large degree of control over thecreation and management of data within a database.

Database management is superior to file processing for a number of reasons:

• It allows a number of users to access the same pieces of data at the same time - for example, three people on different computers can access thesame word file simultaneously through database management
• It allows files to be edited and changed while file processing does not - for example, you may be unable to make amendments to a spreadsheet using file processing
• It allows certain people or users of the database, called administrators, to have more control than other users, whereas in file processing, all users have the same amount of control

I have heard the term used in the now moribund sport of slot racing. there was an arbitray switching of lanes ( different colors coded- and normally Orange, the center lane had the tactical advantage. while some tracks had more lanes- only 8 were used in a race. the rules required on change lanes with each qualifying heat- this was called a Round-Robin. Idea was to equalize the tactical angles. In baseball, it might refer to a rotation of pitchers, for example. The term rather oddly derives from the fact a Robin is a migratory bird- and makes (round()trips. It is used also in stamp collector"s clubs but I am not sure of the meaning. Round-Robin, usually hyphenated is not to be confused with the song Rockin" Robin.