Test 1 Flashcards
(35 cards)
What is an attribute?
They are a name and a data type for data
database is a tree-like hierarchy, folders with subfolders
Hierarchical
database is one big hashmap
Key-Value Pair
What is the minimum number of attributes in a relation?
0 called an anti table
A relation can be pictured as a…
table
a set of attributes whose values with always uniquely identify a tuple in the relation
candidate key
constraints to prevent inconsistencies
Data Integrity
defines what sort of data is stored
Data Definition Language
a super-set of a candidate key
super-key
The columns of a table are called …
attributes
a set of possible values
domain
What are the candidate keys for a tuple with no attributes?
The empty set
Every true piece of information is in the database
No false data is in the database
Using null violates the closed universe assumption
Null represents missing information
Closed universe assumption
What is the maximum number of attributes in a relation?
No maximum
What is a domain
A set of values and a data type
accessing and processing data
Data Manipulation Language
most common form of database
Relational
prevents unauthorized access or modification of data
Data Security
Each attributes has an associated
domain
DBMS provide..
Data Definition Language,
Data Manipulation Language,
Data Security,
Data Integrity
Tables are organized into
schemas
a seperation of how data is physically stored and organized from how data is logically accessed
Data Abstraction
A relation with 0 attributes, how many tuples can there be in that relation?
1
The rows of a table are called
tuples
