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Alex Onsman has Published 203 Articles
![Alex Onsman](https://www.tutorialspoint.com/assets/profiles/13357/profile/60_91536-1512482971.jpg)
Alex Onsman
674 Views
Many users consider Primary Key as Unique Key, since both uniquely identify a table, but Unique Key is different from Primary Key. Unique Key accepts null values and Primary Key cannot have null.Let us compare Primary Key and Unique Key and understand its concept −UsageA Unique Key is used to ... Read More
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Alex Onsman
2K+ Views
Structural IndependenceStructural independence exists when changes in the database structure do not affect DBMS ability to access data.Structural dependence exists when changes in the database structure do not affect DBMS ability to access data.Data IndependenceThe changes done in the lower level will not affect the upper layers. The two types are ... Read More
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Alex Onsman
4K+ Views
What is 4NF?The 4NF comes after 1NF, 2NF, 3NF, and Boyce-Codd Normal Form. It was introduced by Ronald Fagin in 1977.To be in 4NF, a relation should be in Bouce-Codd Normal Form and may not contain more than one multi-valued attribute.ExampleLet us see an example −Movie_NameShooting_LocationListingMovieOneUKComedyMovieOneUKThrillerMovieTwoAustraliaActionMovieTwoAustraliaCrimeMovieThreeIndiaDramaThe above is not in ... Read More
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Alex Onsman
22K+ Views
What is Transitive DependencyWhen an indirect relationship causes functional dependency it is called Transitive Dependency.If P -> Q and Q -> R is true, then P-> R is a transitive dependency.To achieve 3NF, eliminate the Transitive Dependency.ExampleMovie_IDListing_IDListing_TypeDVD_Price ($)M08L09Crime180M03L05Drama250M05L09Crime180The above table is not in 3NF because it has a transitive functional ... Read More
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Alex Onsman
5K+ Views
For Entity Integrity Rule, each table has a Primary Key.Primary Key cannot have NULL value.Student_IDStudent_AwardsStudent_AwardsAbove, you can see our primary key is Student_ID. We cannot consider Student_Awards as the primary key since not every student would have received the award.Let us see another example −Employee_IDEmployee_NameEmployee_AgeEmployee_LocationIn the above table, the Primary ... Read More
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Alex Onsman
6K+ Views
Data Dictionary consists of database metadata. It has records about objects in the database.What Data Dictionary consists ofData Dictionary consists of the following information −Name of the tables in the databaseConstraints of a table i.e. keys, relationships, etc.Columns of the tables that related to each otherOwner of the tableLast accessed ... Read More
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Alex Onsman
312 Views
Normalization removes data redundancy and update, insert and delete anomalies and gives you a normalized perfect database design that a database administrator love.To normalize a database table, follow the below given steps that highlights the role of normalization forms and its uses −First Normal Form (1NF)1 INF is useful in ... Read More
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Alex Onsman
3K+ Views
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 ... Read More
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Alex Onsman
10K+ Views
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 ... Read More
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Alex Onsman
425 Views
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 ... Read More