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Define entity integrity and referential integrity. How does SQL allow specification of these?
Ans: Entity Integrity Rule- If the attribute A of relation R is a prime attribute of R after that A cannot accept null values.
Referential Integrity Rule- In referential integrity, it is made sure that a value that appears in one relation for a given set of attributes as well appears for a particular set of attributes in another relation.
In SQL, referential integrity and entity integrity rules are implemented as constraints on the relation known as reference Key constraint and primary Key constraint correspondingly.
These constraints can be fixed with relation at the time of creation of the relations or after the creation of the relations by altering the definition of the relations. For instance:
, write the relational schema, and draw the new dependency diagrams. Identify the normal forms for each table structure you created
Discuss the count function? The COUNT function used returns the number of tuples or values fixed in a query. The count function comprises two types of syntax: (1) COUNT (*)
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Define single valued and multivalued attributes. Single valued attributes: attributes with a single value for a particular entity are known as single valued attributes. Mult
In this assignment, you will create a program that works with multiple tables. In this assignment, you will work with the factory and sales tables. 1. Create a new project nam
Eliminate Repeating Groups The problem is, "Find out the list of employees, who knows DB2". For this problem we require to perform an awkward scan of the list looking for re
as a customer service employee, explain five measures you would recommend a displeased student to patronise a school canteen
How to create values of structured type? Constructor functions are used to make values of structured types. A function with the similar name as a structured type is a construct
What is a PROJECT operation? The project operation is a unary operation that returns its argument relation with particular attributes left out. Projection is shown by pie (π).
Use of partial data by applications : In common, applications work with views rather than whole relations. Thus, it may be more appropriate to work with subsets of relations rather
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