DBMS Basics - Interview Questions and Answers
What is Set-at-a-time or Set-oriented?
The High level or Non-procedural DML can specify and retrieve many records in a single DML statement. This retrieve of a record is said to be Set-at-a-time or Set-oriented.
What is Relational Algebra?
It is procedural query language. It consists of a set of operations that take one or two relations as input and produce a new relation.
What is Relational Calculus?
It is an applied predicate calculus specifically tailored for relational databases proposed by E.F. Codd. E.g. of languages based on it are DSL ALPHA, QUEL.
How does Tuple-oriented relational calculus differ from domain-oriented relational calculus?
- The tuple-oriented calculus uses a tuple variables i.e., variable whose only permitted values are tuples of that relation. E.g. QUEL
- The domain-oriented calculus has domain variables i.e., variables that range over the underlying domains instead of over relation. E.g. ILL, DEDUCE.
What is normalization?
It is a process of analysing the given relation schemas based on their Functional Dependencies (FDs) and primary key to achieve the properties
(1).Minimizing redundancy, (2). Minimizing insertion, deletion and update anomalies.
What is Functional Dependency?
A Functional dependency is denoted by X Y between two sets of attributes X and Y
that are subsets of R specifies a constraint on the possible tuple that can form a
relation state r of R. The constraint is for any two tuples t1 and t2 in r if t1[X] =
t2[X] then they have t1[Y] = t2[Y]. This means the value of X component of a tuple
uniquely determines the value of component Y.