Computer knowledge

   Semantic Data Model in DBMS pdf: Semantic Object Model introduction: The semantic object model is a logical representation of data in an organization. It views the entire computer network system as a collection of objects related to one another. The semantic object model takes semantic objects as the basic element. It is based on the concepts presented by Codd engineer. It was first presented in 1988. The semantic object model can represent the perceptions of the users more closely than the E-R model. Semantic Objects: A semantic object is a thing that can be identified in the user's working environment. Semantic means "meaning". Semantic objects are used to represent or model the meaning of the user's data.  Semantic objects are grouped into classes. Each object has a unique name. For example, different classes in a university are STUDENT, Teacher, and DEPARTMENT, etc. A particular semantic object is known as an instance of the STUDENT class, "Abdullah" ...

   Database Recovery Techniques in DBMS Database Failure: In every computer database management system, there is a possibility of computer hardware or computer software failure. The failures may occur without warning. The data in the database may be lost or damaged due to the failures of DBMS. After a failure occurs, a DBMS should recover the information that was entered into the database. Reasons for Database Failure: The most common failures are as follows: Failure of a computer system Break down of hardware. Program bugs User mistakes Types of Failures: Generally, there are two types of failure: System Failure A computer system failure is also said to be an instance of failure. It is a failure of the main memory of a computer system. Computer system failures may be caused by a power failure of a database, an application or operating system crash, memory error, or some other reason. The end result is the unexpected termination of the database management system software. Medi...

   Concurrent Execution of a Transaction in DBMS pdf Transaction: A transaction is defined as a logical unit of work that they required. It consists of more or more operations on a database that must be completed together so that the database remains in a consistent state.  Suppose any type of information on the stock is stored in the database. The database stores two things i.e. sold list and quantity, This is one operation on the database. However, the quantity of the sold item n must also is subtracted from the items currently in stock. If both steps are not completed together, the database will be in an inconsistent state. The number of items in stock will be wrong if items are sold but not subtracted from items in stock.  Commit and Rollback: A transaction is committed if it completes successfully and changes any type of data. if it fails and leaves the data unchanged, it is said that the transaction has been rolled back. Transaction properties (ACID properties)...

  What is MS Access and its Features?  Microsoft ACCESS: It is a relational management system (RDBMS). It is used to store and manipulate a large amount of information which is not specific. It is very easy to understand for users. Its graphical interface helps different users to create queries, forms, and reports very easily. Even an inexperienced programmer can use MS access to perform different activities which he required. The process of entering, updating data, and reporting information to become very easy. Starting MS Access: The following procedure can be used to start MS Access step by step: Click the START button on the taskbar and select the Programs menu item. The program's submenu will be displayed. Click the Microsoft Access program item. MS Access will be started. OR Double click on the Microsoft Access icon on Desktop if it appears. Application Window of MS Access: MS Access Application window follows the standard layout of all computer Microsoft applications so...

   Reference Architecture of DDBMS Centralized Database System: A type of database system in which all system components reside at a single computer or site is known as a Centralized database system. The system components include database and DBMS etc. Distributed Database System: A type of database system in which the database is stored physically across computers or sites at different locations is known as a distributed database system. The sites of a distributed database may be spread over a large area connected via a wide area network (WAN) or over a small area such as a building or a campus connected via a local area network. Decentralized Database: A type of database system in which the database is stored on computers or sites at different locations is known as a decentralized database system. In a computer decentralized database, the computer system is not interconnected via a network. So the users at various sites cannot share data of any type. It is a collection of in...

client-server database in DBMS Client-Server Architecture              Client-server architecture is a network of computers. It consists of two types of computers known as clients and servers. The client computers process applications and server computers provide services to client computers such as database processing.             The client-server  database system is based on a client-server architecture. In this computer database system, the server computer stores and processes a database in a computer system. The client computers use the database by sending requests to the server computer. Client-Server Processing In client-server processing, application programs perform the following tasks: Process the user interface Invoke application logic Enforce some business rules Calls the DBMS for database service. The call is normally given in SQL management. The DBMS performs the following tasks. Process SQL statem...

 System Development Life Cycle Tutorialspoint Introduction: A system can be defined as a combination of some related components of files that interact with one another to perform some specific tasks. Our main discussion here is focused on the computer Application Software development process, leaving aside the different software packages which are always available in all markets. To develop a system, several distance faces are to be a workout. For this purpose, SDLC was developed, which is an organized way to develop a successful system. It involves 5 phases as shown System Development Components: The system component comprises of the following necessary components Hardware Software People/Users Data/Information Communication setup Five Phases: It involves seven phases as shown below Preliminary investigation analysis design coding testing implementation maintenance System Development Life Cycle: Preliminary Investigation: The objective of the preliminary investigation is to conduc...