Database Concepts: Questions and Answers

Posted on Dec 16, 2024 in Computers

Database Fundamentals: Q&A

Questionnaire 1

1. What method is needed for flexible storage and retrieval of large amounts of data?
   Management System Database (DBMS)
2. What is a set of data elements that describes itself with relations between these elements?
   Database
3. What is a relationship?
   It’s a sense of unity that exists between certain data elements.
4. Mention the 5 models of database:
   
   • Relational
   • Object Oriented
   • Deductive
   • Network
   • Hierarchical
5. What is the most popular database model?
   Relational model.
6. What is an abstract method for organizing data elements and their relationships?
   Model database.
7. What is the role of a data dictionary?
   Used to resolve entity references that appear in application service requests.
8. Mention and explain the three levels of database services:
   
   • Physical level: deals with storage structures
   • Conceptual level: represents custom views
   • External level.
9. What are the responsibilities that a database administrator (DBA) must assume?
   
10. Keep the conceptual scheme.

Claiming operating parameters. Establish valid user accounts and access privileges. Monitor backup and recovery operations. Arbitrate conflicting suggestions from users for changes in database structure or access privileges. What isolates the problems of storing and retrieving data in large volume on the computer?
System database.

Questionnaire 2

1. Joint specified by enumeration or by a predicate.
   Domain.
2. It is an ordered pair (N, D) where N is the YD is a Domain Name.
   Attribute.
3. It is a set of associations.
   Tuple.
4. Finite set of relations where each of them contains a relational schema and a corresponding body.
   Relational Database.
5. Application-specific connection between multiple entities.
   Relationship.
6. It is the number of entities involved.
   Degree of relationship.
7. Mention the 3 types of relationships.
   From one to many, many to many, one to one.
8. It is the relationship in which an entity involving more than one time, assume a different role in each entry in the relationship.
   Related resources.
9. Limit the data that appear in the bodies of relations.
   Restricted Database.
10. Constitute an annotation to document an attempt of a Design Database.
    ER Diagram.

Questionnaire 3

1. What is relational algebra?
   It is a system of operations on relations, is a closed system because each operation returns a new relationship, which can then serve as operator for further operations.
2. What are the names of the seven basic operators of relational algebra?
   The union, set difference, Cartesian product, selection, projection, name change and aggregation.
3. What basic operators should have the same number of attributes, and tribute must carry the same names?
   The union and set difference.
4. Does the basic function of this operator is to form all the possible concatenation of the form (x: y), with the taking of an operand prefix and suffix borrowed from another?
   The Cartesian product.
5. What basic operators conducting operations in horizontal and vertical sections respectively?
   The selection and projection.
6. What basic operator tuples isolated groups that have common values in certain attributes chosen and each group reduces to a single tuple?
   The operator added.
7. What type operations may be natural union?
   Associative and commutative.
8. At that type of query is a candidate tuple contributes wing command response if a path to a tuple anchor?
   Existential Search
9. At that kind of consultation, a tuple contributes wing candidate commands a response if trajectories package that fully embrace a set of tuples anchor?
   Universal Search
10. Is a method of writing otherwise the expressions of relational algebra to increase efficiency while maintaining functional equivalence?
    Query optimization

Questionnaire 4

1. What are the predicates?
   The functions that return true or false
2. What are simple predicates?
   They are the atomic
3. What is WFF?
   A well-formed formula
4. Any WFF that is assembled?
   Atomic predicates using connectives and quantifiers Logic
5. What is a notation that personalizes the traditional predicate calculus to a particular database?
   Tuple relational calculus
6. With which we can calculate an attribute value?
   With constant
7. How existential query as meet the requirements of each element?
   By assigning a path to some tuple anchor
8. A universal query qualify an element?
   When you assign a package paths sufficient to produce some set of anchors
9. What type of variable using the tuple relational calculus?
   It varies on the group of tuples in the database
10. What type of variable is used the domain relational calculus?
    They vary on the union of all domains in the database

Questionnaire 5

1. What is a list of comma?
   It is a list of items separated by commas that specifies the attributes of answer.
2. What is a Cartesian product of a set of relationships?
   It’s a new relationship tuples containing all possible combinations of tuples from the original relations.
3. What is a subquery?
   It’s a select statement embedded in a query assistant hostess.
4. Remove and identify inappropriate combinations anchor?
   The Boolean expression in the WHERE clause
5. Subqueries appearing in solving universal SQL query?
   A set of tuples calculates the anchor and the other the calculated set of tuples accessible
6. It is a conceptual grouping of the tuples of Cartesian product in order to perform calculations on the attribute values within each group?
   A Partition
7. Specify ORDER BY clause?
   Specify a key sequence classification
8. What is an aggregate?
   It’s a function that operates in a specified column
9. That makes the optional GROUP BY clause?
   Divide the horizontal section of the Cartesian product
10. It adds new tuples to database tables:
    The INSERT