Distributed Database Collection of several interconnected databases which are physically distributed to different locations and they can communicate over a computer network is called Distributed Database. Features of Distributed Database The databases in the collection are logically linked. They often represent a single logical database. Data is physically stored in multiple locations. The data of each location can be managed...

Definition of Schedule A schedule is a process in which a single group of multiple parallel transactions is created and executed individually. You must maintain the order in which the instructions appear in each transaction. If two transactions are executed at the same time, the result of one transaction can influence the result of another transaction. Below is the example:...

Database Transaction A transaction can be defined as a task group. A single task is the minimal processing unit, which cannot be further divided. ACID Properties of Transaction The small unit of a program which can contain several low-level tasks is called transaction. A database transaction should maintain atomicity, consistency, isolation, and durability. These properties are known as ACID properties....

Object Oriented Database Systems The object-oriented database management system is the data model where data are stored in the form of objects, instances of classes. This system is also known as ODBMS. Together, these classes as well as objects form an object-oriented data model. Components of Object Oriented Data Model OODBMS is based on three main components: object structure, object...

Fifth Normal Form (5NF) If a relation is in 4NF as well as does not contain any join dependency as well as joining is lossless then the relation is in 5th normal form. When the tables are broken into as many tables as possible in order to avoid redundancy then it can be said that 5NF is satisfied. 5th Normal...

First Normal Form (1NF) – A relation is 1NF if it contains an atomic value. It indicates that an attribute of a table cannot contain multiple values. It can only contain one attribute with a single value. The first normal form does not allow the multivalued attribute, the compound attribute as well as its combinations. Example: The EMPLOYEE relationship is...

DBMS Anomalies There are three types of anomalies that occur when the database is not standardized. These are anomalies when inserting, updating as well as deleting. Let’s take an example to understand this. Example: Suppose a manufacturing company stores the employee details in a table called employees with four attributes: emp_id to save the employee ID, emp_name to save the...

Join Operation A join operation combines linked tuples of different relationships if and only if a particular join condition is met. It is noted ?. For example, if there are two tables: EMPLOYEE and SALARY; Evaluation: ∏EMP_NAME, SALARY (EMPLOYEES ?. For example, if there are two tables EMPLOYEE and SALARY; Evaluation: (EMPLOYEE ?. For example, if there is two tables...

Definition of Relational Database The relational database management system consists of all modern database management systems, such as SQL, MS SQL Server, IBM DB2, Oracle, My-SQL and MS-Access. Data is displayed in groups (rows) in RDBMS. A relational database is the most commonly used database. It contains several tables, and each table has its own primary key. The RDBMS was...

Network Model It is an extension of the hierarchical model. In this model, the data is organized graphically and may have more than one main node. In this database model, the data is more closely linked because more relationships are established in this database model. Since the data is more closely linked, access to the data is also easier and...