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RDBMS Interview Questions - Part 4


What is DML Compiler ?

It translates DML statements in a query language into low-level instruction that the query evaluation engine can understand.

What is Query evaluation engine ?

It executes low-level instruction generated by compiler.

What is DDL Interpreter ?

It interprets DDL statements and record them in tables containing metadata.

What is Record-at-a-time ?

The Low level or Procedural DML can specify and retrieve each record from a set of records. This retrieve of a record is said to be Record-at-a-time.

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
  • Minimizing redundancy
  • 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.

    RDBMS Interview Questions - Part 5 >>>




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