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Technical articles with clear explanations and examples
The benefits of good Database Design
A good database design has many benefits and is a goal to achieve for every DBA −Easy Retrieval of InformationIf the design is developed properly, then it would be easier to retrieve information. Correct design means the tables, constraints, and relationships created are flawless.Easier ModificationChanges that you make to the value of a given field will not adversely affect the values of other fields within the table.Easy to MaintainThe database structure should be easy to maintain. The design is perfect if changes in one field is not affecting changes in another field.InformationWith a good design, you can enhance the quality ...
Read MoreMany-to-Many Relationship in DBMS
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.
Read MoreDatabase Design Methodologies
Database Design Methodologies has phases to guide the designer for assistance. The Methodology has a structured approach to help in the design process.The following are the phases/ models −Conceptual PhaseThe Conceptual phase lets you know the entities and the relation between them. It describes the conceptual schema. The entities & relations are defined here.Logical PhaseLogical data model provides details about the data to the physical phase. The physical process gives ER Diagram, data dictionary, schema, etc that acts as a source for the physical design process.Physical PhaseThe physical database design allows the designer to decide on how the database will ...
Read MoreHistory of Data Models and Databases
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 MoreTypes of Entity Relationships in DBMS
Entity in DBMS can be a real-world object with an existence, For example, in a Company database, the entities can be Employees, Department, Project, etc. In a College database, the entities are Profession, Students, Result, Activities, etc.An entity is represented as a single rectangle, shown belowThe following are the entity relationships −One-to-One RelationshipUnder One-to-One (1:1) relationship, an instance of entity P is related to instance of entity Q and an instance of entity Q is related to instance of entity P.Let us see an example −A person can have only one passport, and a passport is assigned to a single person.One-to-Many RelationshipUnder ...
Read MoreIdentifying Entity Relationships in DBMS
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 MoreEvolution of Data Models
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 MoreGetting an error while previewing swf file from XML data in SAP Dashboard Designer
There could be multiple reasons that this error comes up. Try below steps:Adobe Global Security Settings changesMade entries in windows host file andAdded SAP server as trusted site in IEThis purely seems to be a security setting issue in Adobe Flash Player. There are various SAP notes that you can search however I am not aware any relevant one.
Read MoreUsing SAP RSECNOTE tool to display information for ABAP and Java Stack
In SAP system, you can use tools like RSECNOTE and SAP EarlyWatch Alert which can be to find out the patches and verify their implementation status. You can access RSECNOTE by executing Transaction code: SA38 or ST13.RSECNOTE tool in SAP system is used to determine which important security notes or hot notes are missing in a system.You can refer more details about this tool in SAP OSS Note 888889. You can access this tool by calling T-Code: ST13 and entering RSECNOTE and then press F8 button.888889 - Automatic checks for security notes using RSECNOTE (outdated)You use transaction ST13 to start ...
Read MoreJava labelled for loop
Following program is using labeled for loops. Example public class Tester { public static void main(String args[]) { first: for (int i = 0; i
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