Quiz 2 Flashcards
The columns range of permissible values is known as its
Domain
an attribute or combination of attributes that uniquely identifies any given row
Primary key (pk)
A_____consists of one or more attributes that determine other attributes
Key
____ is the state in which knowing the value of one attribute makes it possible to determine the value of another
Determination
the value of one or more attributes determines the value of one ore more other attributes
Functional dependence
the attribute whose value determines another is called ____
Determinant
The attribute whose value is determined is called____
Dependent
a key that is composed of more than one attribute
Composite Key
an attribute that is part of a key is called ____
Key Attribute
a key that can uniquely identify any row in the table
superkey
is a minimal superkey– a superkey without any unnecessary attributes
candidate key
is the condition in which each row in the table has its own unique identity
Entity integrity
the abscence of any data value, and is never allowed in any part of the primary key
Null
is the primary key of one table that has been placed into another table to create a common attribute
foreign key
is defined as a key strictly for data retrieval purposes
Secondary key
relational operators have the property of _____; that is, the use of relational algebra operators on existing relations produces new relations
closure
some designers use special codes called_____to indicate the absence of some value
codes
_____theoretical way of manipulating table contents
Relational algebra
what are the 8 relational operators
SELECT, PROJECT, JOIN, INTERSECT,UNION,DIFFERENCE, PRODUCT, DIVIDE
when a table contains the same number of columns and compatible domain it is called
Union compatible
Links tables on the basis of an equality condition that compares specified columns of each table
Equijoin
only returns matched records from the tables that are being joined
Inner Join
Inner join plus all cells that don’t have a match
Outer Join
provides a detailed description of all tables in the database
data dictionary
detailed systems data dictionary, contains metadata
System catalog
a ______ table is the implementation of a composite entity
linking table
an orderly arrangement used to logically access rows in a table
Index
the index’s reference point
index key
