Chapter 3: The Relational Database Model Flashcards
the column’s range of permissible values
domain
is an attribute or combination of attributes that uniquely identifies any given row
primary key
consists of one or more attributes that determine other attributes
key
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 that the value of one or more attributes determine the value of one or more other attributes.
functional dependence
the attribute whose value determines another
determinant
the attribute whose value is determined by the other attribute
dependent
used to refer functional dependencies in which the entire collection of attributes in the determinant is necessary for the relationships
full functional dependence
a key that is composed of more than one attribute
composite key
an attribute that is a part of a key
key attribute
a key that can uniquely identify any row in the table
superkey
a minimal superkey- that is a superkey without any unnecessary attributes
candidate key
the condition in which each row in the table has its own unique identity
entity integrity
the absence of any data value and it is never allowed in any part of the primary key
null
the primary key of one table that has been placed into another table to create a common attribute
foreign key (FK)
the condition in which every reference to an entity instance by another entity instance is valid
referential integrity
a key that is used strictly for data retrieval purposes
secondary key
involved when a table record is considered for deletion
delete rules
apply when a new record is about to be inserted into a table
insert rules
apply when an existing record is about to be updated
update rules
rule that states if an attempt is made to delete a record in one table where on or more records with matching foreign key values exist in another table, all associated records will be deleted
cascade delete rule
rule that states that if an attempt is made to delete a record in one table where one or more records with matching foreign key values exist in another table, that the delete operation will not be allowed
restrict delete rule
rule that states if an attempt is made to delete a record in one table where one or more records with matching foreign key values exist in another table, then the foreign key values are set to NULL so we know that the record they used to point to has been deleted
set-to- null delete rule
all primary key entries are unique, and no part of a primary key may be null
requirement of entity integrity
a special code to avoid nulls to indicate the absence of some value
flag
an orderly arrangement used to logically access rows in a table
index
the index’s reference point
index key
the index key can have only one pointer value
unique index
