In the era now of course we are already familiar with the computer. Computers are essential to support the productivity and helping people work becomes easier. Of course we have to know more and more about this computer world. Writers on this post will explain the database and data files. May be useful for us in order not to lay with this computer.
Understanding Database, File Data
Database is a set of data (data warehouse), which consists of multiple data files where each file is interrelated.
- Data files are where data is stored inside the Data Table.
- Table data is a collection of some data that is represented by some of the attributes of the data source (objects / events)
- A collection of several interrelated data table called data base system.
- The process for managing data in a database file called System Management Database.
File Type Database
1. Master File (Master File)
There are two types of master files are:
- Parent File Reference (reference master file)
Recordnya data is relatively static and rarely changed value
Example: file payroll, course.
- Dynamic Master File (dynamic master file)
Value of recordnya frequently changed or updated as a result of a transaction.
Example: file inventory.
2. File Transactions (Transaction File)
Also called the input file. Used to record the data of the transaction. Sample files Sale of Goods.
3. File Report (Report File)
Also called the output file. Contains temporary information to be displayed as a report.
4. File History (history file)
Also called an archive file (archieval file). Is a file that contains the data of the past is no longer active, but still kept on file.
5. File Backup (backup file)
A copy of the files that are still active in the database at any given moment. Used as a backup if the active database file is damaged or missing.
- Data hierarchy
Data hierarchy consists of the File, Record and Data Element.
Data Element / Field / Attributes
The smallest unit of data which can no longer be solved other units that are more meaningful.
Recording / Record / Line
The combined number of data elements that are interrelated.
File / File / Table
Set records that have similar long-attributes / fields are the same, but different data contents.
- Database Definition Language
Language Database is a link or intermediary between the user / user with database interaction. The existence of the language of databases, users can access the data in the database.
Can be divided into two, namely:
Data Definition Language (DDL)
DDL language is basic commands that are used to process the database. This language is used to create a new table, create index, alter table, determine the structure of the table storage. The compilation is a collection DDL command table stored in a special file called a data dictionary.
Data Manipulation Language (DML)
Database language is useful for manipulation and retrieval of data in a data base, manipulation may include insertion, deletion and modification of data in a database. DML aims to facilitate consumer / user to access the data.
- Understanding of Database Systems
Database System can be defined as a collection of files / tables that are related. The main component of the database system, namely Hardware (hardware), OS (operating system), Database (database), Management Tool Database (DBMS), User (user), applications (software) other (optional) ,
Hardware contained in the database system include:
- Computer (either standalone or in a network / network)
- Secondary memory on-line (hard drive)
- Secondary off-line memory (disk backup)
- Media / Communication Device (for network systems)
The operating system is a program that activates / functioning of a computer system, controlling all the resources in the computer and perform basic operations in a computer (input / output operations), file management, and so forth.
- Example StandAlone OS: MS Windows, Linux, Unix standalone version.
- Examples of network systems OS: Version MS Windows Server, Linux Server Version)
- Database Architecture
Database architecture is divided into three levels, namely:
- 1. Level Internal / physical (Physical Level)
Is the lowest level, which describes how the physical storage of data and Manage the allocation of physical and index data storage and management associated with the file to store and access data.
- 2. Level Concept (Conseptual Level)
Used to describe what data will be stored, said entities and attributes. Data will be stored and represented in multiple files / tables that are related. At the level of this concept also states logic structure.
- 3. Level view (View Level)
At this stage only shows a portion of the database that needs to be displayed to the user. In addition, it also defines certain parts correspond to a specific group, provides a display / interface that is different for each user and tailored to the needs of each authority, and converting the original data / data into meaningful physical / logical on the User.
Objectives and Benefits Database
Speed and Simplicity (speed), efficient storage space, the accuracy (Acuracy), safety (security), maintaining the alignment of the data, the same data can be shared (shared), and applicable standards.
- User (user)
- system Engineer
Experts who are responsible for the installation of Database Systems, and also held improvement and reporting errors from the system to the user.
- Database Administrator (DBA)
Experts who have a duty to control the overall database system, predicting the need for the system database, plan and organize.
Types of Users
Programmer Application, Advanced User, General User (End User), User Custom (Specialized / Sophisticated User)
Example Usage Database
- Bank: Management of customer data, accounting, all banking transactions
- Service: reservation data management, scheduling
- University: Management of enrollment, graduates
- Sales: Management of customer data, product, sales
- Factory: Management of production data, inventory, ordering, agents
- Personnel: Management of employee data, payroll, taxes
- Telecommunications: Management of billing data, the number of pulses
the independence of the Data
With their level at the architecture level, there arises the independence of the Data.
The independence of data is ketidakbergantungan data so changes to a certain level will not affect the other levels.
There are 2 kinds of Independence Data:
The independence of data logically
Concept Scheme changes will not affect the other levels.
As an example:
The addition of the attributes is possible without having to rewrite the application program, only need to edit a program that is not too complex.
The independence of physical data
Changes in the physical schema will not affect the schema concept.
As an example:
Index additions will not affect the level of concepts but can affect the data access speed (faster) on the View Level.