Identity 
Like a library, secondary storage is created to store information. How is this stored information organized? What are databases, and why do we need to know everything about them?
Just a few days ago, a computer was considered an island with limitations on accessing information outside of its own hard disk. Now, through communication networks and the Internet, personal computers have direct electronic access to almost unlimited sources of information.
In today's world, almost all information is stored in databases. Schools, hospitals, And it is an important part of almost every institution, including banks. In order to survive in today's competitive world, you need to find information and understand how it is stored.
To use computers effectively and efficiently, you need to understand data fields, records, tables, and databases. You need to know the different ways to design databases, and the different types of databases. Also, be aware of the most important uses and issues of databases.
Data
People in Information Systems, Procedures. Software,. It can be defined as facts or observations about people, places, objects and events. To put it more clearly, this case sheds light on how databases store, organize, and use data.
Not long ago, data was limited to the numbers, letters, and symbols recorded by keyboards. Now the data is very rich and included.
Sound and voice recognition systems captured, interpreted and stored using microphones.
Music downloaded from the Internet and stored on smartphones, tablets, and other devices.
Photographs taken by a digital camera, edited by image editing software, and sent to others via the Internet. There are two ways to view video_ data created on digital video cameras, TV tuner cards, and webcams. They are perspectives
- Physical View and Logical Physical View sheds light on the actual format and location of the data. As seen in Chapter 5, data is recorded in digital beats that are specially formed in bytes representing characters using a coding system such as Unicode. In a nutshell, only computer professionals with special skills come into contact with the physical view. The second approach sheds light on the logical view, the meaning of the data, the subject matter and the context. End users and most computer professionals belong to this approach. They engage with application programs in the actual use of data. This case presents a logical view of the data and how the data is stored in databases.
Organizing Data
The first step in understanding data bases is to learn how data is organized. Organized into logical views, data groups, or categories. Each group is more complex than the previous one.
- Character: A character is the most basic logical data element. It is a single letter, number or special symbol, such as a punctuation mark, or a symbol such as om.
- Field: The next upper level is the field or group of related characters. In your example. Brown is in the data field for an employee's last name. It contains individual characters There are those who make surnames. The data field describes the
- properties of certain units (persons, places, objects or things). For example, an employee is a unit with many attributes, including his or her last name.
- Record: A record is a collection of related fields. A record is a collection of attributes that describe a unit. In your example, an employee's payroll record contains fields describing an employee's characteristics. These attributes are first name, last name, employee ID and salary.
- Table: A table is a collection of related records. For example, the payroll table will contain information (recorder) of payroll (units) for employees.
- Database: A database is an integrated collection of logically related tables. For example, the personal database will include all relevant employee tables, including payroll tables and benefits tables.
Key Field
Each record in a table contains at least one specific field called a key field. This field record, also known as the primary key field, distinguishes it. Tables can be related or common key fields can be linked to other tables.
For most employee databases, a key field is the employee identification number. Key fields from different tables can be used to integrate data into a database. For example in Perth, personal databases contain field staff IDs in both payroll and benefits tables. The data in both the tables can be linked by attaching all the records with the same key field (employee ID).
batch versus real time processing
tradition, data is processed in one of two ways. These two methods, batch processing or what you might call "letter (later)" and real time processing or what you might call "now (now)", are used to handle general record-keeping tasks such as payroll and sales orders.
Batch Processing: In batch processing, data is collected over several hours, days or even weeks. It is then processed as a whole "batch" at the same time. If you have a credit card, your bill probably reflects batch processing. Each time, an electronic copy of the transaction is sent to the credit card company.
Real-Time Processing: Real-time processing, also known as online processing, occurs when data is processed while a transaction is taking place. For example, every time you request funds at an ATM, real-time processing takes place. After you provide account information and request a specific withdrawal, the bank's computer verifies that your account has sufficient funds. If so, you are then funded, and the bank promptly updates your account balance.
Databases
Multiple organizations have multiple files on the same topic or individual. For example, may appear in customer files. This is called data redundancy, if the customer changes location, the address in each file must be updated. If one or more files are ignored, problems can arise. For example, an ordered product may be sent to a new address but the bill may be sent to the old address. This situation arises due to lack of data integrity. Furthermore.
data scattered in different files here and there is not as useful. The marketing department, for example, may want to offer some special promotions to a customer who places a lot of orders for merchandise. To find this customer. The marketing department will need permission to view the files in the billing department. This can be done more efficiently if all the data is in a shared database. A database can provide the information you need.
Knowing the need for databases
For an organization, there are several benefits to having databases:
- Exchange: In organizations, information from one department can be quickly exchanged with others. Billing marketing can allow customers to place large orders for merchandise.
- Security: Users are given passwords or access to the information they need. In this way, the payroll department can reach the rate of salary of the employee but not other departments.
- Reduce data redundancy: Without a shared database, each department will have to create its own data, which will result in data redundancy. For example, an employee's home address may appear in several files. Redundant data results in unnecessary use of storage space and data maintenance problems.
- Data Integrity: When there are multiple sources of data, each source may have some differences. One customer's address may be listed as "Main Street" in one system and "Main Street" in the other system.
Database Management
Special software is required to create, modify, and use a database. This software is called a database management system, commonly abbreviated as DBMS.
Some DBMSs, such as Microsoft Access, are designed specifically for personal computers. Other DBMS are designed for sjpecialized database servers.
DBMS software consists of five subdivisions or subsystems: DBMS Engine, Data Definition, Data Manipulation, Application Generation, and Data Administration.
DBMS engine provides a bridge between logical view and physical view of data. When the user requests for data (logical approach), DBMS Engine handles the details of actually finding the data (physical approach).
Data Definition Subsystem determines the logical structure of a database using a data dictionary or schema. This dictionary describes the structure of the data in a database. For a particular case of data, it specifies the names to be used for that particular field. It specifies the type of data (text, numeric, time, graphic, audio, and video) for each field.
The Data Manipulation subsystem provides tools for the analysis and maintenance of data. Data maintenance is called data maintenance. This includes adding new data and editing existing data. Analysis Tool to view all data or selected part of data, query database, And helps create reports. Specific tools include programming languages called Query-by-Exemplary and Structured Query Language (SQL). (Structured query languages and other types of programming languages will be discussed in Chapter 13).
The application generation subsystem provides tools to create specialized programming languages such as C ++ or Visual Basic that interface with working data entry force and commonly and widely used programming languages. Including data administration subsystem security, providing disaster recovery support, and monitoring the overall performance of database operations. In the management of the entire database
