Many-to-Many relationship in DBMS is a relationship between more than one instance of an entity with more than one instance of another entity i.e. both the entities can have many relationships between each other.The relation can be stated as −Let us see an example −Many Authors can write a Book, whereas an Author has written more than one book.Here, Book and Author are entities.Let’s say a book has two authors, whereas an individual author has written six books till now.

An attribute is fully functional dependent on another attribute, if it is Functionally Dependent on that attribute and not on any of its proper subset.For example, an attribute Q is fully functional dependent on another attribute P, if it is Functionally Dependent on P and not on any of the proper subset of P.Let us see an example −ProjectIDProjectCost00110000015000EmpIDProjectIDDaysE099001320E056002190The above relations states that −Days are the number of days spent on the project.EmpID, ProjectID, ProjectCost -> DaysHowever, it is not fully functional dependent.Whereas the subset {EmpID, ProjectID} can easily determine the {Days} spent on the project by the employee.This summarizes ... Read More

Database Design can be a tiresome task and you would need to follow the below approach and tackle the challenges to get a well-designed database.The concerns and challenges with Database design are the following −Following Design StandardsConsidering Design Standards while designing a database is quite essential. It gives you components that are well defined. With this, you can also easily evaluate an existing design.If you are unable to follow the design standards approach, then do not expect the design to be proper and you will not be able to evaluate it.Achieving High Processing SpeedEveryone needs faster access for the relationships ... Read More

Relationships in DBMS can be stated as a relation between two entities like Employee-Department, Student-Course, etc.One-to-One relationship in DBMS is a relationship between an instance of an entity with another.The relation can be stated as −An Employee is issued an Employee ID Card. An individual employee is offered a unique ID card in the company. Here, Employee and ID Card (ID_Card) are entities.

Managing data was the key and was essential. Therefore, data model originated to solve the file system issues. Here are the Data Models in DBMS −Hierarchical ModelIn Hierarchical Model, a hierarchical relation is formed by collection of relations and forms a tree-like structure.The relationship can be defined in the form of parent child type.One of the first and most popular Hierarchical Model is Information Management System (IMS), developed by IBM.ExampleThe hierarchy shows an Employee can be an Intern, on Contract or Full- Time. Sub-levels show that Full-Time Employee can be hired as a Writer, Senior Writer or Editor:AdvantagesThe design of ... Read More

BigData and NoSQL are the choice for database solutions nowadays, but that does not mean the crucial features of RDBMS will die. Since 90% of the world data produced in last some years, therefore the need for RDBMS will not end in the near future.The RDBMS market is incrementing with 9% annual growth, as stated by Gartner, a research company. RDBMS is meant to handle organized data. NoSQL and Big Data maybe a preferred choice, but the importance of RDBMS will not end in near future.Managing data on a large scale now needs technologies like Big Data, but RDBMS still ... Read More

Good Database Design is what everyone wants to achieve to avoid the consequences of dealing with a bad design.The following are the objectives of a good database design −Avoid Redundant DataThe table in the database should be constructed following standards and with utmost dedication. It should have different fields and minimize redundant data. The table should always have a Primary Key that would be a unique id.Faultless InformationThe database should follow the standards and conventions and provide meaningful information useful to the organization.Data IntegrityIntegrity assists in guaranteeing that the values are valid and faultless. Data Integrity is set to tables, ... Read More

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 More

Identifying entity relationships in DBMS is used to identify a relationship between strong and weak entity.Before beginning, let us take an example of Professor entity, which is our Strong Entity, with Professor_ID as a Primary Key −Professor_IDProfessor_NameProfessor_CityProfessor_SalaryThe weak entity is Professor_Dependents entity:NameDOBRelationNow, let us continue, Weak EntityWeak Entity is dependent on Strong Entity and does not have a primary key. Weak Entity has a partial key. It is represented as double rectangle −Strong EntityOther entities are dependent on Strong Entity and it has a key attribute i.e. a primary key and represented as a single rectangle.Identifying RelationshipsIt links the strong and weak entity ... Read More

The history of data models had three generations of DBMS −Hierarchical System was the first generation of DBMS. The first generation also came with the CODASYL system. Both of them introduced in 1960s.The second generation includes the Relational Model. Dr. E.F.Codd introduced it in 1970.The third generation includes Object-Relational DBMS and Object-Oriented DBMS.The history timeline of databases is shown below −File based systemsFile based systems came in 1960s and was widely used. It stores information and organize it into storage devices like a hard disk, a CD-ROM, USB, SSD, floppy disk, etc.Relational ModelRelational Model introduced by E.F.Codd in 1969. The ... Read More