Concept explainers
Normalization:
The process used to minimize data redundancy and dependency in a relational
First normal form (1NF):
- If a table does not contain any replicate fields or groups of fields then that model is called as first normal form.
- In this form, entities do not contain any single instance of the repeating variable.
- It means that the entities contain only one instance of the attributes, multi-valued attributes are neglected.
Second normal form (2NF):
- The value of all non-primary key attributes should be dependent on the primary key attribute.
- If any attribute is depending on the partial primary key then it should determine the other attributes for an instance of the entity.
- The partial dependencies should be removed from the data model.
Third normal form (3NF):
- The value of any non-primary key attributes will not depend on any other non-primary key attributes.
- If any non-primary key attributes depend on any other non-primary key attribute then it should be moved or deleted.
- It is termed as transitive dependency.
Partial dependency:
A partial dependency exists at that time of an attributes depends only a part of primary key. This dependency is related with 1st normal form.
Transitive dependency:
A transitive dependency exists at that time of an attributes depends on another attribute which is not part of primary key.
Functional dependency:
An association between two attributes or two set of attributes in a same relational database table, which is having some constraints is known as functional dependency.
- In a table one attribute is functionally dependent on another attribute to take one value.
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Chapter 6 Solutions
DATABASE SYSTEMS-MINDTAPV2.0
- How to develop a C program that receives the message sent by the provided program and displays the name and email included in the message on the screen?Here is the code of the program that sends the message for reference: typedef struct { long tipo; struct { char nome[50]; char email[40]; } dados;} MsgStruct; int main() { int msg_id, status; msg_id = msgget(1000, 0600 | IPC_CREAT); exit_on_error(msg_id, "Creation/Connection"); MsgStruct msg; msg.tipo = 5; strcpy(msg.dados.nome, "Pedro Silva"); strcpy(msg.dados.email, "pedro@sapo.pt"); status = msgsnd(msg_id, &msg, sizeof(msg.dados), 0); exit_on_error(status, "Send"); printf("Message sent!\n");}arrow_forward9. Let L₁=L(ab*aa), L₂=L(a*bba*). Find a regular expression for (L₁ UL2)*L2. 10. Show that the language is not regular. L= {a":n≥1} 11. Show a derivation tree for the string aabbbb with the grammar S→ABλ, A→aB, B→Sb. Give a verbal description of the language generated by this grammar.arrow_forward14. Show that the language L= {wna (w) < Nь (w) < Nc (w)} is not context free.arrow_forward
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- Database Systems: Design, Implementation, & Manag...Computer ScienceISBN:9781285196145Author:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos CoronelPublisher:Cengage LearningA Guide to SQLComputer ScienceISBN:9781111527273Author:Philip J. PrattPublisher:Course Technology PtrDatabase Systems: Design, Implementation, & Manag...Computer ScienceISBN:9781305627482Author:Carlos Coronel, Steven MorrisPublisher:Cengage Learning