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Explain the Project-Join normal form
A relation R is in PJNF along with respect to a set of functional dependencies D if for all join dependencies of the outline *(R1, R2, ...,Rn) and R = R1 U R2 U ..., URn at least one of the subsequent holds:
*(R1, R2, ...,Rn) is trivial
Each Ri is a superkey of R
What are the objectives of query processing? Ans: The objectives of query processing is to transform a query written in a high level language into a accurate and efficien
What is trigger? Triggers are statements that are executed automatically by the system as the side effect of a modification to the database.
Compare the Nested-loop join and block-nested loop join Ans: Nested loop join - It is costly as worst case cost, no. of block accesses needed is n r * b s + b r where b
What is Identity? Identity (or AutoNumber) is a column that automatically produces numeric values. A start and increment value can be set, but most DBA leave these at 1. A GUID
Data Definition Language It organises the data in the form of columns and rows. But what does the data field column of table accumulate? How do you describe it using SQL? Th
What is the difference between WHERE and HAVING clauses?. Predicates in the WHERE clause applies to every tuple while the predicate in the HAVING clause applies to groups.
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
What is the max. no. Of structures that can be included in a table or structure. Nine.
Type of database technology
how to design tables
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