Database Programming

A paper-based system can only be organized in a single way, cannot be easily searched, cannot be easily modified, cannot be accessed remotely, cannot be conveniently cross-referenced, maintained and updated, protected, and cannot be expanded without considerable effort.

Computerized databases solve nearly all of these problems.

Whereas a paper-based system would need extensive labor and reorganization in order to change the sequence and order of data, a digital database could be re-ordered instantly with a single click; thus, data could immediately be re-sorted based on (for example) a customer's name, address, age, average order size, credit rating, etc. Then, the digital version could be re-sorted by another criteria... and then another, all in just a few seconds.

A paper system would require extensive time and man-power to search for a given piece of information, whereas a digital database could instantly find the required data in any field, instantly. Further, a database system could cross-reference data, finding matches within multiple fields, correlate them, perform arithmetic processes on them, and retrieve only the data that matches every single criteria. For example, it could find a list of every customer in a database with an 'A' credit rating who is engaged in heavy construction projects, who has spent more than $40,000 with your company within the past year, and whose current fleet of bulldozers is more than 15 years old... perhaps the perfect lead for your bulldozer sales representatives. To find, analyze and correlate this data by hand would take nearly a lifetime.

A paper system cannot be easily modified and expanded. Updating data requires removing each record's card or file, erasing the old data (or waiting while white-out dries because a former employee violated the 'pencil only' rule), and then carefully entering it again. For bulk updates and batch changes, every single record must be found and updated individually. If the original filing system wasn't conceived to take new fields into consideration, you'll resort to writing on the backs of cards, or meticulously writing in margins, or adding pages to filing systems that were designed for a single page per record. Not so with computer-based databases. Batch updates take seconds, with a click-and-drag function. Need to expand data? No problem, just add a field to the entire database with a single click. Did the law recently change, prohibiting certain information from being maintained on clients? Or does the law now require new accountability for record keeping? Examples could include the FOIA (Freedom of Information Act), or the HIPAA (Healthcare Information Privacy and Accountability Act), or any number of ever-changing state and federal regulations for nearly any industry. With a paper database, you may well be out of business, but with a digital database, you're instantly back in compliance with just a few clicks.

A paper system requires massive amounts of space, climate control, fire protection, lighting, etc. These all add overhead to your operation, whether in the home environment, or a high-level corporate record keeping firm. The paper is a risk, in and of itself, to life and safety due to accidental fire concerns. Paper files are subject to damage from temperature, water (floods, hurricanes), fire, theft, accidental loss and mis-ordering (which, depending on the size of the filing system, could be catastrophic and impossible to correct), and are almost impossible to back-up completely, requiring that an entire new system be duplicated from scratch, perhaps by hand. This dilemma is what prompted the now-obsolete technologies of microfilm and microfiche (essentially condensed photographic slides of files) -- so that data could be archived to save space and backup valuable data. On the other hand, a digital database of nearly any size could reside on a single computer or small network. Perfect digital backups of data can be made instantly to protect against any loss. With a small amount of care and diligent and frequent archiving (perhaps even automatically), there is no reason that there should ever be data loss; these convenient backups can survive and maintain an office's operations, regardless of any threat to the original data, up to and including catastrophes and acts of God. Further, data in a computer database could be encrypted during storage, to prevent any theft or unauthorized copying of information.

Further, whereas an old-fashioned paper file must be visited to be used, for example the card catalogs that are disappearing from libraries everywhere, a digital database, if appropriate and desirable, can be accessed remotely from anywhere, either securely by authorized users, or publicly by anyone connected to the internet. Digital databases fuel internet revenue, essentially allowing buyers to check a business's current stock of merchandise, then automatically edit the inventory sheets when they make their purchase. That sure beats counting items manually, or risking embarassing cancellations for orders when a surprise glitch in the paper filing system shows inventory that doesn't exist, or has been sold.

A business's paper-based system could even be discontinued, and proprietary-sized paper, forms, or storage could become impossible to obtain. The advantages of digital databasing systems over a paper system are innumerable.

· Cost effectiveness

· Employment

· Process time

· Access to up-to-date information

· Globalization - IT has not only brought the world closer together, but it has allowed the world's economy to become a single interdependent system.

· Communication - With the help of information technology, communication has also become cheaper, quicker, and more efficient.

· Bridging the cultural gap - Information technology has helped to bridge the cultural gap by helping people from different cultures to communicate with one another.

· More time - IT has made it possible for businesses to be open 24 x7 all over the globe. This means that a business can be open anytime anywhere.

· Creation of new jobs - Probably the best advantage of information technology is the creation of new and interesting jobs. Computer programmers, Systems analysers, Hardware and Software developers.

Disadvantages

· Unemployment - While information technology may have streamlined the business process it has also crated job redundancies, downsizing and outsourcing.

· Privacy - Though information technology may have made communication quicker, easier and more convenient, it has also bought along privacy issues.

· Lack of job security - Industry experts believe that the internet has made job security a big issue as since technology keeps on changing with each day.

· Dominant culture - While information technology may have made the world a global village, it has also contributed to one culture dominating another weaker one. For example it is now argued that US influences how most young teenagers all over the world now act, dress and behave.

Depending on the company, they could be the same. But, if they are different, here is the difference:

A data administrator is one who oversees the data integrity of the database. They do not create objects and they may not have privileges to do anything other than "view" the data and report any data discrepencies to the database administrator(one who administers the entire database). The data administrator can check data in the tables to make sure there are no errors, can check to see if tables that need an index have one, are all programs valid--stuff like that. The database administrator is usually busy with fixing problems, creating tablespaces, tables, looking at error messages.

Sudipto Chattopadhyay

Discuss the distinction between centralized and decentralized conceptual database design:.

Centralized and decentralized design constitute variations on the bottom‑up and top‑down approaches we discussed in the third question presented in the discussion focus. Basically, the centralized approach is best suited to relatively small and simple databases that lend themselves well to a bird's‑eye view of the entire database. Such databases may be designed by a single person or by a small and informally constituted design team. The company operations and the scope of its problems are sufficiently limited to enable the designer(s) to perform all of the necessary database design tasks:

1. Define the problem(s).

2. Create the conceptual design.

3. Verify the conceptual design with all user views.

4. Define all system processes and data constraints.

5. Assure that the database design will comply with all achievable end user requirements.

The centralized design procedure thus yields the design summary shown in Figure Q6.6A.

Figure Q6.6A The Centralized Design Procedure

Note that the centralized design approach requires the completion and validation of a single conceptual design.

Note: Figures 6.15 and 6.16 contrast the two design approaches, Figure 6.6 shows the procedure flows; demonstrate that such procedure flows are independent of the degree of centralization.

In contrast, when company operations are spread across multiple operational sites or when the database has multiple entities that are subject to complex relations, the best approach is often based on the decentralized design.

Typically, a decentralized design requires that the design task be divided into multiple modules, each one of which is assigned to a design team. The design team activities are coordinated by the lead designer, who must aggregate the design teams' efforts.

Since each team focuses on modeling a subset of the system, the definition of boundaries and the interrelation between data subsets must be very precise. Each team creates a conceptual data model corresponding to the subset being modeled. Each conceptual model is then verified individually against the user views, processes, and constraints for each of the modules. After the verification process has been completed, all modules are integrated in one conceptual model.

Since the data dictionary describes the characteristics of all the objects within the conceptual data model, it plays a vital role in the integration process. Naturally, after the subsets have been aggregated into a larger conceptual model, the lead designer must verify that the combined conceptual model is still able to support all the required transactions. Thus the decentralized design activities may be summarized as shown in Figure Q6.6B.

Figure Q6.6B The Decentralized Design Procedure

Keep in mind that the aggregation process requires the lead designer to assemble a single model in which various aggregation problems must be addressed:

¨ synonyms and homonyms. Different departments may know the same object by differentnames (synonyms), or they may use the samename to address differentobjects(homonyms.) The object may be an entity, an attribute, or a relationship.

¨ entity and entity subclasses. An entity subset may be viewed as a separate entity by one or more departments. The designer must integrate such subclasses into a higher‑level entity.

¨ Conflicting object definitions. Attributes may be recorded as different types (character, numeric), or different domains may be defined for the same attribute. Constraint definitions, too, may vary. The designer must remove such conflicts from the model.

A database is used for storing your work and is a easy way to store information

A database is crucial for storing information, providing information to multiple users, easy access to data, fast information recall, and increased efficiency particularly for business owners.

Storing Information

A database is a type of file system that stores information. This is its most basic function. Instead of relying on traditional methods of storing information in physical file folders and cabinets, a database provides digital storage of information.

Providing Information To Multiple Users

Big advances in database technology allows multiple users to access and update information. This information will then be instantly viewable by all users. Not only does this enhance communication within a company, but it also ensures an informed and positive approach to customer service.

Easy Access To Data

A database manager provides easy access to information. Because the information is centralized, the user has no need to look to other applications or sources. All is provided through a singular database system, and the information in the database can be repurposed and fed into a company Web site or blog.

Fast Information Recall

Due in part to a series of complex algebraic algorithms that work together to recall information easily, querying a database should produce a quick result. When compared to locating the information manually, users find this quick recall an attractive feature of databases.

databases are used to store information from medical to personal.

you can use a database for

• recording results of a survey
• teaching
• bookings

A database is useful for storing information in it.

database are used to organise data into a more formal and understandable structure

Databases are used to reduce the redundancy and manage the data base of the employees more effectively and in a better way..

integrity of data can be provided , security of imp. data and easy retrieval of the desired information can be done

So database must be maintained to keep our data safe and secure....