Theoretical

Question 1

SQL language basis

Answer 1

Relational model for querying and managing data based on ANSI and ISO standards

Question 2

Imperative vs declarative programming

Answer 2

The easiest way to explain the difference between declarative and imperative code, would be that imperative code focuses on writing an explicit sequence of commands to describe how you want the computer to do things, and declarative code focuses on specifying the result of what you want.

Question 3

SQL uses which paradigm

Answer 3

Declarative, that is, to specify, what I want to get not how I want to get something

Question 4

What are the categories of statements in SQL

Answer 4

Data definition language (DDL), Data manipulation language (DML), and data control language (DCL)

Question 5

DDL

Answer 5

Object definition- create, alter, drop.

Question 6

DML

Answer 6

Data manipulation language- select, insert, delete, update, truncate, and merge

Question 7

DCL

Answer 7

Data control language, Grant and revoke

Question 8

T-sql subset or superset?

Answer 8

Both, hahaha

Question 9

Set theory

Answer 9

Georg cantor, By a “set” we mean any collection M into a whole of definite, distinct objects m (which are called the “elements” of M) of our perception or of our thought.

Question 10

Set definition

Answer 10

Set and set definitions ‘ are
Not supported by proofs/ they are axioms

Question 11

Whole

Answer 11

A set should be considered a single entity . Collection of objects as opposed to an individual object.

Question 12

Distinct

Answer 12

Every element of a set must be unique, to have key in a row

Question 13

“Our perception of one thought”

Answer 13

Definition of a set is subjective

Question 14

Object

Answer 14

Abstract objects

Question 15

No mention of order

Answer 15

Older is not important

Question 16

Set of tuples

Answer 16

Rows in SQL

Question 17

Predicate logic

Answer 17

Dr. Edgar F. Codd
Managements querying of data

Question 18

A predicate

Answer 18

A property, or an expression that either holds or doesn’t hold true I false. Predicates as parameterized propositions.

Question 19

The relational model

Answer 19

A semantic model day for - management and manipulation that is based on set theory and predicate logic

Question 20

Relational model

Answer 20

The goal of the relational model is to enable consistent representation of data with minimal or no redundancy and without sacrificing completeness, and to define data integrity (enforcement of data consistency) as part of the model

Question 21

Goals of an RDBMS

Answer 21

An RDBMS is supposed to implement the relational model and provide the means to store, manage, enforce the integrity of, and query data.

Question 22

What does a relational model

Answer 22

The relational model involves concepts such as propositions, predicates, relations, tuples, attributes, and more

Question 23

Propositions, predicates & relations

Answer 23

A key point in the relational model is that a single relation should represent a single set (for example, Customers). Note that operations on relations (based on relational algebra) result in a relation (for example, a join between two relations).

Question 24

First version of the relational model (Codd,1969, IBM)

Answer 24

“Derivability, Redundancy, and Consistency of Relations Stored in Large Data Banks.” A revised version was proposed by Codd in 1970 in a paper called “A Relational Model of Data for Large Shared Data Banks,”

Question 25

What are the goals of a relational model ?

Answer 25

The goal of the relational model is to enable consistent representation of data with minimal or no redundancy and without sacrificing completeness, and to define data integrity (enforcement of data consistency) as part of the model. An RDBMS is supposed to implement the relational model and provide the means to store, manage, enforce the integrity of, and query data.

Question 26

# Propositions, predicates and relations "Relational" true meaning

Answer 26

“Relational” actually pertains to the mathematical term relation. In set theory, a relation is a representation of a set. In the relational model, a relation is a set of related information, with the counterpart in SQL being a table—albeit not an exact counterpart. A key point in the relational model is that a single relation should represent a single set (for example, Customers). Note that operations on relations (based on relational algebra) result in a relation (for example, a join between two relations).

Question 27

Proposition

Answer 27

A proposition is an assertion or a statement that must be true or false.

Question 28

Closed-world assumption

Answer 28

If a proposition is true, it will manifest itself as a row in a table of Employees. A false proposition simply won’t manifest itself.

Question 29

A type (predicate)

Answer 29

A type is one of the most fundamental building blocks for relations. A type constrains an attribute to a certain set of possible or valid values.

Question 30

Missing values

Answer 30

True, False, Unknown (NULL) | Null marker

Question 31

Constraints

Answer 31

Data integrity is achieved through rules called constraints that are defined in the data model and enforced by the RDBMS. The simplest methods of enforcing integrity are assigning an attribute type with its attendant “nullability” (whether it supports or doesn’t support NULLs). Constraints include candidate keys, which provide entity integrity, and foreign keys, which provide referential integrity

Question 32

Candidate key

Answer 32

A candidate key is a key defined on one or more attributes that prevents more than one occurrence of the same tuple (row in SQL) in a relation. | A predicate based on a candidate key can uniquely identify a row (such a

Question 33

Foreign key

Answer 33

Foreign keys are used to enforce referential integrity. A foreign key is defined on one or more attributes of a relation (known as the referencing relation) and references a candidate key in another (or possibly the same) relation.

Question 34

Normalization

Answer 34

The relational model defines normalization rules (also known as normal forms). Normalization is a formal mathematical process to guarantee that each entity will be represented by a single relation.

Question 35

ERM | Entity relationship modelling

Answer 35

https://en.wikipedia.org/wiki/Entity%E2%80%93relationship_model

Question 36

1NF

Answer 36

The first normal form says that the tuples (rows) in the relation (table) must be unique and attributes should be atomic. This is a redundant definition of a relation; in other words, if a table truly represents a relation, it is already in first normal form.

Question 37

3NF

Answer 37

1. The data must meet the second normal form, 2. All monkey attributes must be dependent on candidate Keys nontransitively That is, all non key attributes must be mutually independent

Question 38

2NF

Answer 38

1. Data must meet the 1 nf 2. The relationship between non- key and candidate key. For every candidate key, every non-key alleibute has to be fully functionally dependent on the entire candidate key.in other words.

Question 39

Two main types of systems, or workloads, use SQL server as their database . Uses t-sol to manage and manipulate the data

Answer 39

Online transactional processing (OLTP) and data warehouse (DWs)

Question 40

Entity relationship model [ definition]

Answer 40

Describes inter-related things of interest in a specific domain of knowledge,. In software engineering, used to represent things a business needs to perform business processes. - it is also used as an abstract data model, that defines a data or information structure which can be implemented in a database typically a relational database.

Question 41

Classes of database systems.

Answer 41

OLTP: online transactional processing DSA: data-staging area DW: data warehouse ETL: extract, transform, and load

Question 42

ERM - schema