Friday, 6 February 2015

Commonly asked RDBMS interview questions and answers (Page 3)

21. What is an attribute? | RDBMS Questions
It is a particular property, which describes the entity.

22. What is a Relation Schema and a Relation? | RDBMS Questions
A relation Schema denoted by R(A1, A2, …, An) is made up of the relation name R and the list of attributes Ai that it contains. A relation is defined as a set of tuples. Let r be the relation which contains set tuples (t1, t2, t3, ..., tn). Each tuple is an ordered list of n-values t=(v1,v2, ..., vn).

23. What is degree of a Relation? | RDBMS Questions
It is the number of attribute of its relation schema.

24. What is Relationship? | RDBMS Questions
It is an association among two or more entities.

25. What is Relationship set? | RDBMS Questions
The collection (or set) of similar relationships.

26. What is Relationship type? | RDBMS Questions
Relationship type defines a set of associations or a relationship set among a given set of entity types.

27. What is degree of Relationship type? | RDBMS Questions
It is the number of entity type participating.

25. What is DDL (Data Definition Language)? | RDBMS Questions
A data base schema is specifies by a set of definitions expressed by a special language called DDL.

26. What is VDL (View Definition Language)? | RDBMS Questions
It specifies user views and their mappings to the conceptual schema.

27. What is SDL (Storage Definition Language)? | RDBMS Questions
This language is to specify the internal schema. This language may specify the mapping between two schemas.

28. What is Data Storage - Definition Language? | RDBMS Questions
The storage structures and access methods used by database system are specified by a set of definition in a special type of DDL called data storage-definition language.

29. What is DML (Data Manipulation Language)? | RDBMS Questions
This language that enable user to access or manipulate data as organized by appropriate data model.
? Procedural DML or Low level: DML requires a user to specify what data are needed and how to get those data.
? Non-Procedural DML or High level: DML requires a user to specify what data are needed without specifying how to get those data.
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