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In tuple relational calculus P1→ P2 is equivalent to ?
A In tuple relational calculus P1→ P2 is equivalent to ¬P1 V P2. (The logical implication expression A B, meaning if A then B,is equivalent to ¬A V B)
What is data independence? Data Independence: Techniques which permit data to be changed without affecting the applications in which procedure it. There are two types of data
Backward Recovery (UNDO): In this system the uncommitted changes made by a transaction to a database are undone. Instead the system is reset to the last consistent state of databa
During the deletion of a tuple two cases can happen: Deletion of tuple in relation having the foreign key: In this type of case simply delete the desired tuple. For example, in
When are they useful? Justify with an example. The temporary tables are commonly used to support specialized rollups or exact application processing needs. Unlike a permanent t
Describe Physical Data independence ? Physical Data Independence - It is capacity to modify the internal schema without having to change conceptual schema. Therefore, the exter
What is the use of integrity constraints? Integrity constraints make sure that changes made to the database by authorized users do not result in a loss of data consistency. The
The Second Normal Form (2NF) Definition: A relation is in 2NF if it is in 1NF and each non-key attribute is fully dependent on each candidate key of the relation. Some of th
why three level architecture had been developed/
Consider the two relations given below Given that A is the primary key of R, D is the primary key of S and there is a referential integrity among S.A and R.A, discuss all
Q.1 Briefly discuss the different layers of ANSI SPARC architecture. Ans: The three layers of ANSI SPARC architecture are like this: 1. Internal view is at the lowest leve
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