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DBMS Articles
Page 8 of 27
Condition of schedules to View-equivalent
View-equivalence is a term used in database management systems to describe the circumstance in which two schedules, when applied to the same database, yield the same result set. This requirement is necessary to guarantee data correctness and consistency in database applications. There are requirements that schedules must meet in order to achieve view equality. These circumstances are − Conflict Serializability − The conflicting operations in a schedule must be performed in the same sequence for it to be conflict serializable. Operations that access the same data item and at least one of which affects the data are said to ...
Read MoreConcept of Time in database
In the form of a relation, a database is used to mimic the status of some part of the real world outside. Database systems, in general, store just one state, which is the present state of the actual world, and do not keep data regarding prior and past states, except sometimes as audit trails. If the real world's current state changes, the database is edited and updated, and knowledge about the previous state is lost. But, in the majority of real-world applications, it is important to store and retrieve information about previous states. A student database, for example, must have ...
Read MoreComputer-based control in Database
This article will provide a broad review of computer-based controls before moving into the computer-based controls in databases available in a multi-user database system. Let's discuss all of them one by one. A group of security procedures called computer-based controls are used in DBMSs to safeguard the database against illegal access, alteration, or destruction. These safeguards are intended to guarantee that the database can only be accessed by authorized users and that the data is safe from accidental or deliberate destruction. Physical controls and administrative processes are only a couple of the several remedies available to deal with threats to ...
Read MoreComplex Type Structures for Objects and Literals
Complex type structures for objects and literals are also crucial in the context of database management systems (DBMS). In this context, difficult types refer to data types that can store multiple values within a single column or attribute. This allows for more efficient and organized storage of complex data, such as arrays or nested objects, in a database. When it comes to databases, complex type structures for objects and literals can be incredibly useful for storing and retrieving data efficiently. In this article, we will explore how complex type structures can be implemented in databases, their advantages, and some of ...
Read MoreComponents and Analysis of Star Schema Design
Star schema design is a type of database schema used in data warehousing that is designed to make querying and analyzing large datasets more efficient. The schema consists of a central fact table that contains the data to be analyzed and one or more dimension tables that provide additional information about the data in the fact table. Components of Star Schema A star schema is made up of four major components. These are as follows − Fact Table Dimension Table Attributes Attribute Hierarchies Let us go over them one by one − Facts These are monetary ...
Read MoreWhat is the purpose of Database Management System?
The Database Management System (DBMS) is defined as a software system that allows the user to define, create and maintain the database and provide control access to the data.It is a collection of programs used for managing data and simultaneously it supports different types of users to create, manage, retrieve, update and store information.PurposeThe purpose of DBMS is to transform the following −Data into information.Information into knowledge.Knowledge to the action.The diagram given below explains the process as to how the transformation of data to information to knowledge to action happens respectively in the DBMS −Previously, the database applications were built ...
Read MoreTypes of dependencies in DBMS
Dependencies in DBMS is a relation between two or more attributes. It has the following types in DBMS −Functional DependencyFully-Functional DependencyTransitive DependencyMultivalued DependencyPartial DependencyLet us start with Functional Dependency −Functional DependencyIf the information stored in a table can uniquely determine another information in the same table, then it is called Functional Dependency. Consider it as an association between two attributes of the same relation.If P functionally determines Q, thenP -> QLet us see an example −EmpIDEmpNameEmpAgeE01Amit28E02Rohit31In the above table, EmpName is functionally dependent on EmpID because EmpName can take only one value for the given value of EmpID:EmpID -> EmpNameThe same is displayed ...
Read MorePartial Dependency in DBMS
What is Partial Dependency?Partial Dependency occurs when a non-prime attribute is functionally dependent on part of a candidate key.The 2nd Normal Form (2NF) eliminates the Partial Dependency.Let us see an example −ExampleStudentIDProjectNoStudentNameProjectNameS01199KatieGeo LocationS02120OllieCluster ExplorationIn the above table, we have partial dependency; let us see how −The prime key attributes are StudentID and ProjectNo, andStudentID = Unique ID of the studentStudentName = Name of the studentProjectNo = Unique ID of the projectProjectName = Name of the projectAs stated, the non-prime attributes i.e. StudentName and ProjectName should be functionally dependent on part of a candidate key, to be Partial Dependent.The StudentName can be determined by StudentID, which makes the relation ...
Read MoreWhat are the components of DBMS?
Hardware, Software, Data, Database Access Language, Procedures and Users all together form the components of a DBMS.Let us discuss the components one by one clearly.HardwareThe hardware is the actual computer system used for keeping and accessing the database. The conventional DBMS hardware consists of secondary storage devices such as hard disks. Databases run on the range of machines from micro computers to mainframes.SoftwareSoftware is the actual DBMS between the physical database and the users of the system. All the requests from the user for accessing the database are handled by DBMS.DataIt is an important component of the database management system. ...
Read MoreDDL(Data definition language)
Data Definition Language(DDL) is used for describing data and its relationship in a database. It is also used to define the database schema. The commands only affect the database structure and not the data. The main DDL commands are create, alter, drop and truncate. Create Statement It is used to create a database or table. While creating the table, we specify table_name, column_name followed by data_types(int, float, varchar, etc) and constraints(primary key, not null, etc) Syntax CREATE TABLE table_name ( column1 datatype, column2 datatype, ..... ) Example In this ...
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