What is a system? System is a group of components and elements that are combined into one to achieve certain goals. There are many opinions about the meaning and definition of the system described by some experts.

The following terms and definitions of the system according to some experts:

• Jogianto (2005:2), The system is a collection of elements that interact to achieve a certain goal. This system describes events and a real unity, such as places, objects and people really exist and happen.
• Indrajit (2001:2), is a collection of system-a collection of components that have an element of connection between each other.
• Lani Sidhartha (1995:9), is the set of system parts that are interconnected, which together achieve the same goals.
• Murdick, R. G (1991:27), System is a set of elements that make up the collection or procedures or processing charts are looking for a purpose or goal section along with the operating data and / or goods at a particular reference to generate information and / or energy and / or goods.
• Davis, G. B (1991:45), is a collection of system elements beroperai together to accomplish a goal.

Components or characteristics that make up the system is part of a system, including:

• Object, part, element or variable. It can be physical objects, abstract or both.
• Attributes, is what determines the quality or nature of ownership of the system and its object.
• Internal relationships, a connection between object-objej contained in a system.
• Environment, a place where the system is located.
• Purposes, Every system has a purpose and this purpose is the motivation that drive the system. Without a destination, the system becomes unmanageable. Of course the purpose of the system with other systems differ.
• Input, is something that goes into the system and further into the material to be processed. The input can be things that seem physical (raw materials) or which does not appear (services).
• Process, is the part that does change from input to output more useful and valuable (information) or useless (waste)
• Output, is the result of the process. In the information systems in the form of information or reports, etc.
• Bounds, is a separator between the system and outside the system area. Here define the configuration limits, scope or capabilities of the system. Limits can also be changed or dimodifikai that can change system behavior.
• Control and feedback mechanisms, are used to control the input or process. The goal is to set the system to run in accordance with the objectives.

That was a brief explanation of the meaning and definition of systems, as well as Component and System Characteristics. If anyone wants to add to, please be corrected. May be useful.

In the PL / SQL features available that allow you to write comments in it. In this post, I will discuss about how to make comments between pl sql scripts. In this post, i will share about How to Insert Comments on PL / SQL Scripts.

When PL / SQL you are processed, then the command line or a character that there is a sign (-) or in the sign. Here is How to Insert Comments on PL / SQL Scripts:

• (/ * ... * /) will not be processed.
• ° / * ... * /, the sign is a C language style comments are used for multiple lines. Example: / * I Learning PL / SQL * /

The sign is only useful for one line only. Example: - I Learning PL / SQL.

That was a brief explanation on How to Insert Comments on PL / SQL Scripts. If there are errors or omissions please justified or added. may be useful.

PL/SQL (Procedural Language/Structured Query Language) is Oracle Corporation's procedural extension language for SQL and the Oracle relational database. PL/SQL's general syntax resembles that of Ada or Pascal. It is one of three key programming languages embedded in the Oracle Database, along with SQL itself and Java.

In general, PL / SQL consists of three parts, namely the declaration, part of writing the commands to be executed and the exception.

• The Declaration, This section is optional or not absolutely to be written. Because not all PL / SQL variable or constant need to be declared.
• Writing Commands section, This section is a vital part of a PL / SQL, as if in a PL / SQL are not artifacts of this part of the PL / SQL does not mean anything.
• The Exception, This part is optional and should not be there in a PL / SQL. The usefulness of this section to indicate when an error occurs in the PL / SQL that you create. If you are sure the PL / SQL that you created is correct, then you do not need to write this section.

Here is an example of the general syntax of writing PL / SQL:

DECLARE

             tipe_data variables; - declare variables

             tipe_data constant constant: = value; - declare a constant

             ...

BEGIN

             statement_1;

             statement_2;

             ...

Exception

             THEN WHEN name_exception

             statement_for_handle_error;

             ...

END;

Who can use the database? Database Users very greatly. Not everyone may use the database or databases. Because the database or the database storing data of an enterprise (company, organization, school, etc.) which is very important. So not all can access the database, let alone steal data stored therein.

Database users can be divided into several groups, depending on the level of a user's interests. Here are the classes:
1. Database Administrator (DBA)

• install and upgrade the database
• backup and restore databases
• database contact technical support if there is a disturbance or problem
• perform backup and recovery planning for database information
• ensure compliance with the agreement License Database
• registering users and maintain database security
• modify the database structure
• make the main object of the database (tables, view, index) after finished designing a database developer
• create a database storage structures (tablespaces)
• provides a storage system

2. Security Officer

•     register database users
•     control the user access rights
•     maintaining security systems

3. Application Developer

•     designing a database application
•     estimate data storage requirements for applications
•     modify the database structure for the application
•     convey information as above in the DBA
•     improve the application during development
•     prepare and ensure safety in the development

4. Application Administrator

•     perform operations on the particular application

5. Database User

• users who interact with the database through applications or other assistive devices

6. Network Admin

• connect the database with the user

That was the last brief description of the group from the Database Users. If there are errors or omissions please justified or added. May be useful.

What is a Database Administrator? It is a person who is responsible for a database. Where the DBA has a duty to manage, provide access to anyone who will access the database, etc.. In other words, the Database Administrator (DBA) is a database admin.

The obligation of a database administrator is quite heavy, but it is in accordance with the rights which he acquired. A DBA must know everything about the database, SQL commands and understand about the blocks of PL / SQL. However, if there is a problem on the database system, the DBA is what will solve the problem.

Here are some tasks of a Database Administrator jobs (DBA):

• Installing and Upgrading Oracle software system.
• Installation and maintenance of applications running on the Oracle system.
• Creating a database, tablespace, table, view, index and other database objects.
• Create and monitor user and system usage, including the security system (security).
• Monitoring the use of space (disk) and planning the future development of hardware and software.
• Monitoring the performance of the system (performance tuning) and change the system parameters and optimize the extent required
• Creating a strategy and implement backup and recovery.

In essence, to become a database administrator must master about the database itself, about the relationship, optimization, manage constraints, functions & stored procedures.

That was a brief description of the What is a Database Administrator (DBA). If there are errors or omissions please justified or added. May be useful

In this time, I will discuss about What is Database Architecture. Where am I going to explain some points of view of database users or the database itself.

Database Architecture has some different views. Here are these views of the Database Architecture:

1. External view. Represent the views of individual end users (end user), such as: manager, operator. At this level only interested in a fraction of the whole database / database because the user only uses the data in accordance with the needs and the authority they have. Example: a user part or the personnel concerned with the employee table, and they do not require data on the finance section or table. Thus, the data in the database / data base is done with an external data definition language.
2. Conceptual view. The degree to which the views of users are combined into a single concept of structured and integrated so it becomes a whole new image database / database. Conceptual view (abstract with the actual data is stored) is not the same as the physical data is stored and not the same as the views of the users who use a fraction of the database / database. Thus, the data in the database / data base is done with an external data definition language.
3. Internal view. View of storage that is physically close to the storage. Shows how data is stored, such as paging, clustering, indexing, etc. computer hardware oriented. The media is frequently used computer hard disks, drums, diskettes, hardcard, cd, etc.

That was a brief explanation of What is Database Architecture. If there are errors or omissions please justified or added. May be useful.

In this time, I will discuss about the Components of a Database Systems (System Database). Where is the sense of Database was presented earlier in the previous post. In fact, components used in database is almost the same as the information systems in general. It's just distinguished by the user. Because not everyone can deal directly with the database.

Here are the Components of a Database Systems:
1. Data
The word 'data' comes from the Greek is 'datum' which means the facts. In English, the data is plural. So wrong if we call data. Data is plural, while the datum is a unit and compile the data. Data is stored in terintegritas (integrated), where the facts of the other facts are related. Data can be used together (shared), so that we can use the data without having another lined up to use the data.
2. Hardware
An appliance or device that consists of computer monitors, keyboards CPUm. As well as data communications equipment, etc..
3. Software
Serves as an intermediary between a user with the data in the database. In this case it can be said software is the lifeblood. Examples of such software are: Database Management System (DBMS) like Oracle Postgre, MySQL, etc.. As for the application program to manipulate data, such as the SQL Editor, etc.
4. User
Is anyone using these databases. Here are divided into three classifications for user: Database Administrator (DBA), the person / team in charge of managing the overall database system, Programmer, people / team to program applications that access the database using a particular programming language, and the End User, who access the database through the terminal by using a query language.

Here was my brief explanation of the Components of a Database Systems (System Database). If there are errors or omissions please justified or added. May be useful ..