DB ch3 Flashcards
what is the relation
is a mathematical construct
what is table
is perceived as two dimensional structure composed of row and columns
what is the other name of table
entity set
what is the row called
entity and record
what is the other name of column
attribute and fields
intersection between the row and column represents ?
data value
what is the attribute domain
each column has a specific range of values
what is the principle of determination
functional dependence
definition of functional dependence
is a relationship between two attributes, typically between the PK and other non-key attributes within a table.
true or false
if the attribute (B)is functionally dependent on a composite key (A)but not on any subset of the composite key the attribute (B) if fully functionally dependent on (A)
true
the primary key is not superkey as well as a candidate key
true or false
false
true or false
a null is not permitted in the primary key
true
what is the relational schema
a relational schema is a textual representation of the database tables where each table is listed by its name followed by the list of its attributes in parentheses
what is the foreign key
A FOREIGN KEY is a field (or collection of fields) in one table, that refers to the PRIMARY KEY in another table.
referential integrity
he accuracy and consistency of data within a relationship.
