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MySQL Articles
Page 106 of 355
Major Concerns with Database Design
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 MoreFully-functional dependency in DBMS
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 MoreThe 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 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 MoreDifference between Simple and Complex View in SQL
Before discussing on Simple and complex, first we should know what is View. A View is the logical virtual table created from one or more tables which can be primarily used to fetch the columns from one or more different tables at a time. On the basis of tables involved in the view we can distinguish between Simple and Complex View in SQL.Following are the important differences between Simple and Complex View.Sr. No.KeySimple ViewComplex View1DefinitionSimple View in SQL is the view created by involving only single table. In other words we can say that there is only one base table ...
Read MoreWhat is the difference between BLOB and CLOB datatypes?
Blob and Clob together are known as LOB(Large Object Type). The following are the major differences between Blob and Clob data types.BlobClobThe full form of Blob is a Binary Large Object.The full form of Clob is Character Large Object.This is used to store large binary data.This is used to store large textual data.This stores values in the form of binary streams.This stores values in the form of character streams.Using this you can stores files like videos, images, gifs, and audio files.Using this you can store files like text files, PDF documents, word documents etc.MySQL supports this with the following datatypes:TINYBLOBBLOBMEDIUMBLOBLONGBLOBMySQL ...
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