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Explain Relational model and their use in DBMS?
Relational Model - The relational model was first introduced through E.F. Codd of the IBM Research in the year of 1970. The model uses the concept of a mathematical relation (like a table of values) as its primary building block, and has its theoretical basis in set theory and first-order predicate logic. The relational model presents the database as a collection of relations.
Define the Immediate Update The immediate update methods may apply changes to the database on disk before the transaction arrives a successful conclusion. Though, these change
How does a query tree represent a relational algebra expression? Discuss any three rules for query optimisation, giving example as to when should each rule be applied. Ans
Critically evaluate the bulleted list of information-related items in this case study. How are each contradictory to the notion of being an information-literate knowledge worker?
a. Define the term "deadlock". There are four conditions that must hold before deadlock is possible. Name them. b. Outline an algorithm that detects whether there is a deadlock.
An example of a weak entity is Staff because the availabilityID cannot be uniquely identified unless it is used in conjunction with the foreign key known as availabilityID in the A
Create Student DB and perform delete operation? STUDENT (name, student#, class, major) COURSE (course name, course#, credit hours, department) SECTION (section identifier, co
Differentiate OO development from structured development. Structured approach of problem solving is based upon the idea of decomposition of system into subsystem. In this appro
Describe the Composite Key Composite Key: Sometimes one key is not enough to uniquely recognize a row. E.g. in a single class Roll is enough to search a student, but in the w
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
Identification of concurrency Identification of concurrency: Dynamic model identifies concurrency. Two objects are said to be parallel (concurrent) if they can receive events a
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