Lecture Ch. 4: Relational databases

Question 1

a set up interrelated, centrally coordinated files

Answer 1

database

Question 2

intereface betweeen the database and the application programs that access the data

Answer 2

Database Management System (DBMS)

Question 3

what are the 4 advantages of database system over a file based system

Answer 3

1. allows for data integration
2. minimizes data redundancies and inconsistencies
3. centralized management of the database
4. seperates the logical view from the physical view

Question 4

ways users conceptualize and organize the data

Answer 4

logical view

Question 5

how and where the data is stored

Answer 5

physical view

Question 6

logical organization of database describing the data elements and their relationships

Answer 6

schema

Question 7

how many levels of schema

Answer 7

3

Question 8

what are the 3 levels of schema

Answer 8

1. conceptual level of schema
2. external level schema
3. internal level schema

Question 9

(which of the 3 levels of schema is this)
organization-wide view of all data elements stored in database and the relationship between them

Answer 9

conceptual level schema

Question 10

(which of the 3 levels of schema is this)
set of individual user views of portions of database
* logical views

Answer 10

external level schema

Question 11

(which of the 3 levels of schema is this)
low level view describing how/where data is stored
* physical view

Answer 11

internal level schema

Question 12

decribes the structure of the database and the data elements stored

Answer 12

data dictionary

Question 13

set of commands that all for:
1. creating the database
2. changing the database
3. queerying the database

Answer 13

DBMS languages

Question 14

how many DBMS languages

Answer 14

3

Question 15

what are the 3 DBMS languages

Answer 15

1. data definition language
2. data manipulation language
3. data query language

Question 16

(which of the 3 DBMS languages is this)
set of commands use to create the database
* used to create the data dictionary
* used to establish the logical views of different users
* used to set security restriction, limiting where users can go in the database

Answer 16

data definition language (DDL)

Question 17

(which of the 3 DBMS languages is this)
set of commands to change the database (updating, inserting or deleting)

Answer 17

data manipulation language (DML)

Question 18

(which of the 3 DBMS languages is this)
set of commands used to query or interagate the database

Answer 18

data quiery language (DQL)

Question 19

(which of the DBMS languages you would use for this)
used to create the data dictionary

Answer 19

data definition language (DDL)

Question 20

abstract representation of the contents of the database

Answer 20

data model

Question 21

represents the contents of the database as being stored in the forms of tables

Answer 21

relational data model

Question 22

each row is called a

Answer 22

tuple

Question 23

each row in the table contains data about

Answer 23

1 instince of the entity

Question 24

each column of the table contains data about

Answer 24

a single attribute

Question 25

attribute or combination of contributes that uniquely identify each tuple

Answer 25

primary key

Question 26

every table must have

Answer 26

a primary key

Question 27

an attribute in one table that serves as the primary key in another table - serves to connect the tables in the database

Answer 27

foreign key

Question 28

does every table require a foreign key

Answer 28

no

Question 29

4 key things about tables

Answer 29

1. each cell must be single valued 2. primary key can not be blank 3. foreign keys can be blank, if they arent they must have values that correspond to a primary key in another table 4. all non-key attributes must contain data related to the primary key