intro to database systems

Question 1

where are databases?

Answer 1

everywhere

Question 2

what are some examples of databases?

Answer 2

cloud storage
YouTube
spotify
banks and credit cards
zoom and teams
social media apps

Question 3

instead of the user perspective, what perspective should we think from in this class?

Answer 3

think from the developer’s perspective

Question 4

what is transactional data?

Answer 4

structured data created within an organization, with sizes ranging from gigabytes to terabytes

Question 5

what are some examples of transactional data?

Answer 5

chase bank account data
amazon purchase history

Question 6

what is big data?

Answer 6

data generated by multimedia applications and internet of things

Question 7

what are some examples of big data?

Answer 7

instagram
apple
youtube

Question 8

how does big data differ from transactional data?

Answer 8

in the four v’s: volume, velocity, veracity, and variety

Question 9

what are the four v’s?

Answer 9

volume, velocity, veracity, and variety (the ways big data differs from transactional data)

Question 10

what is volume?

Answer 10

data at rest, big data is much larger than transactional data

Question 11

what is velocity?

Answer 11

data in motion, the speed of streaming data, big data is much faster than transactional data

Question 12

what is variety?

Answer 12

data in many forms, big data has a larger variety than transactional data

Question 13

what is veracity?

Answer 13

uncertainty due to data inconsistency, big data has a higher veracity than transactional data

Question 14

what is the big data equation?

Answer 14

big data = transactions + interactions + operations

Question 15

who is Edgar F. Codd?

Answer 15

he is the author of the research paper on the relational model in 1970 (very important person)

Question 16

how many companies use databases?

Answer 16

a very large amount, banks airlines, and sales are a few examples

Question 17

what is a database?

Answer 17

a very large collection of interrelated data

Question 18

what is a database management system (DBMS)?

Answer 18

a software system designed to store, manage, and facilitate access to databases

Question 19

what are entities and objects?

Answer 19

equivalent statements!

Question 20

what is DBMS?

Answer 20

a software system, NOT a database!

Question 21

when will companies use a filesystem?

Answer 21

when their data isn’t growing

Question 22

when will companies use a database?

Answer 22

when their data is growing

Question 23

what is the SELECT statement in SQL?

Answer 23

the statement used to retrieve data from a database

Question 24

what is the insert into statement in SQL?

Answer 24

statement used to insert new data into a table

Question 25

what are the new demands the 3rd platform brings to databases?

Answer 25

global high availability large data volumes unstructured data transaction rates latency

Question 26

what motivated developers to create the noSQL database?

Answer 26

the new demands the 3rd platform brings

Question 27

what is network latency important to?

Answer 27

developers building applications that can be accessed globally

Question 28

what is the old model of generating data?

Answer 28

few companies produce data, and everyone else consumes data

Question 29

what is the new model of generating data?

Answer 29

everyone generates data, and everyone consumes data

Question 30

it's not just the _________ of information, it's the ___________ of information

Answer 30

quantity, quality

Question 31

why do we use databases?

Answer 31

they allow us to store a lot of content (quantity), while keeping the quality of the data high (lower veracity)

Question 32

what are the drawbacks of using file systems to store data?

Answer 32

data redundancy and inconsistency (duplicate data) difficulty accessing (finding) data data isolation integrity problems (integrity constraints) atomicity of updates concurrent access by multiple users security problems

Question 33

what does a database handle (file systems)?

Answer 33

all of the file system's problems!

Question 34

what does DBMS provide?

Answer 34

efficient, reliable, convenient, and safe multi-user storage of and access to massive amounts of persistent data

Question 35

what are the advantages of databases?

Answer 35

data independence efficient data access data integrity and security concurrent access, crash recovery reduced application development time

Question 36

why would databases not be used?

Answer 36

high costs complexity not suited for special purpose tasks

Question 37

what are the four elements of a data model?

Answer 37

1) data 2) data relationships 3) operations on the data 4) data constraints

Question 38

what is a data model?

Answer 38

a tool for describing its elements

Question 39

what are relationships and tables?

Answer 39

the same thing! (equivalent statements)

Question 40

what are attributes?

Answer 40

the column names of a table (relation)

Question 41

what is a database?

Answer 41

a collection of relations

Question 42

what is a relation schema?

Answer 42

relation name and attribute list (optionally: data types of attributes)

Question 43

what is a database schema?

Answer 43

set of all relation schemas in the database

Question 44

what is an advantage of using a relational database?

Answer 44

it can control the quality of information (lower veracity)

Question 45

what can you use to remember schema?

Answer 45

it is the type of information of a variable in a program

Question 46

what can you use to remember instance?

Answer 46

is is the value of a variable

Question 47

what is an instance?

Answer 47

the actual content of a database at a particular point in time

Question 48

what is SQL designed for?

Answer 48

managing data held in a relational database management system

Question 49

what does SQL consist of?

Answer 49

a data definition language (DDL) and a data manipulation language (DML)

Question 50

what level is data definition at?

Answer 50

the table level

Question 51

what level is data manipulation at?

Answer 51

the data level

Question 52

what are some DDL keywords?

Answer 52

create alter drop

Question 53

what are some DML keywords?

Answer 53

insert update delete select

Question 54

what does create do?

Answer 54

creates a table

Question 55

what does alter do?

Answer 55

changes the table, add, delete, or modify columns

Question 56

what does drop do?

Answer 56

deletes the whole table

Question 57

what does insert do?

Answer 57

allows you to insert data into the table

Question 58

what does update do?

Answer 58

make changes to existing data

Question 59

what does delete do?

Answer 59

deletes data from a table (one row or multiple)

Question 60

what is the most basic element of a table?

Answer 60

an attribute and its type

Question 61

what are the most common attribute types?

Answer 61

INT or INTEGER REAL or FLOAT CHAR(n), fixed length string of n characters VARCHAR(n), variable length string of up to n characters

Question 62

what values can be null?

Answer 62

any value but a primary key

Question 63

how many primary keys can a table have?

Answer 63

at most one

Question 64

can a primary key be null?

Answer 64

NO, NEVER

Question 65

can a table have more than one unique key?

Answer 65

yes

Question 66

can unique keys have null entries?

Answer 66

yes

Question 67

what is the generic syntax to create a multi-attribute key?

Answer 67

PRIMARY KEY (attribute one, attribute two)

Question 68

what is logical data independence?

Answer 68

you can change the logical structure (schema) of the database (add / drop columns), without having to change or update the programs that viewers use the database on

Question 69

what is physical data independence?

Answer 69

you can change the physical structure, basically where the data is stored or how it is stored, without affecting the logical structure or external schema

Question 70

what is external schema?

Answer 70

what the user sees (user views)

Question 71

what is physical schema?

Answer 71

the relations stored in unordered files

Question 72

what is concurrency control?

Answer 72

process of managing simultaneous execution of transactions in a shred database, to ensure the serializability of transactions

Question 73

why do we need concurrency control?

Answer 73

to prevent: 1. lost updates 2. uncommitted data 3. inconsistent retrievals

Question 74

what does logical data independence refer to?

Answer 74

the ability to modify the conceptual schema without affecting external views (how users see the data). It doesn't relate to storage changes.

Question 75

what is an entity?

Answer 75

A real-world object or concept, such as a customer or an account.