WGU C170 Chapter 1|Latest Update Complete
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AREA
In DB2, a named section of permanent storage space that is reserved to store the database.
associative entity
See composite entity.
bridge entity
See composite entity.
candidate key
A minimal superkey; that is, a key that does not contain a subset of attributes that is itself a superkey.
See key.
closure
A property of relational operators that permits the use of relational algebra operators on existing
tables (relations) to produce new relations.
composite entity
An entity designed to transform an M:N relationship into two 1:M relationships. The composite
entity's primary key comprises at least the primary keys of the entities that it connects. Also known as
a bridge entity or associative entity. See also linking table.
composite key
A multiple-attribute key.
dependent
An attribute whose value is determined by another attribute.
determination
The role of a key. In the context of a database table, the statement "A determines B" indicates that
knowing the value of attribute A means that the value of attribute B can be looked up.
DIFFERENCE
In relational algebra, an operator used to yield all rows from one table that are not found in another
union-compatible table.
DIVIDE
In relational algebra, an operator that answers queries about one set of data being associated with all
values of data in another set of data.
domain
In data modeling, the construct used to organize and describe an attribute's set of possible values.
, entity integrity
The property of a relational table that guarantees each entity has a unique value in a primary key and
that the key has no null values.
equijoin
A join operator that links tables based on an equality condition that compares specified columns of
the tables.
flags
Special codes implemented by designers to trigger a required response, alert end users to specified
conditions, or encode values. Flags may be used to prevent nulls by bringing attention to the absence
of a value in a table.
foreign key (FK)
An attribute or attributes in one table whose values must match the primary key in another table or
whose values must be null. See key.
full functional dependence
A condition in which an attribute is functionally dependent on a composite key but not on any subset
of the key.
functional dependence
Within a relation R, an attribute B is functionally dependent on an attribute A if and only if a given
value of attribute A determines exactly one value of attribute B. The relationship "B is dependent on
A" is equivalent to "A determines B," and is written as A B.
homonyms
The use of the same name to label different attributes. Homonyms generally should be avoided. Some
relational software automatically checks for homonyms and either alerts the user to their existence or
automatically makes the appropriate adjustments. See also synonym.
index
An ordered array of index key values and row ID values (pointers). Indexes are generally used to
speed up and facilitate data retrieval. Also known as an index key.
index key
See index.
inner join
A join operation in which only rows that meet a given criterion are selected. The join criterion can be
an equality condition (natural join or equijoin) or an inequality condition (theta join). The inner join is
the most commonly used type of join. Contrast with outer join.
INTERSECT
In relational algebra, an operator used to yield only the rows that are common to two union-
compatible tables.
with A+ Graded Answers
AREA
In DB2, a named section of permanent storage space that is reserved to store the database.
associative entity
See composite entity.
bridge entity
See composite entity.
candidate key
A minimal superkey; that is, a key that does not contain a subset of attributes that is itself a superkey.
See key.
closure
A property of relational operators that permits the use of relational algebra operators on existing
tables (relations) to produce new relations.
composite entity
An entity designed to transform an M:N relationship into two 1:M relationships. The composite
entity's primary key comprises at least the primary keys of the entities that it connects. Also known as
a bridge entity or associative entity. See also linking table.
composite key
A multiple-attribute key.
dependent
An attribute whose value is determined by another attribute.
determination
The role of a key. In the context of a database table, the statement "A determines B" indicates that
knowing the value of attribute A means that the value of attribute B can be looked up.
DIFFERENCE
In relational algebra, an operator used to yield all rows from one table that are not found in another
union-compatible table.
DIVIDE
In relational algebra, an operator that answers queries about one set of data being associated with all
values of data in another set of data.
domain
In data modeling, the construct used to organize and describe an attribute's set of possible values.
, entity integrity
The property of a relational table that guarantees each entity has a unique value in a primary key and
that the key has no null values.
equijoin
A join operator that links tables based on an equality condition that compares specified columns of
the tables.
flags
Special codes implemented by designers to trigger a required response, alert end users to specified
conditions, or encode values. Flags may be used to prevent nulls by bringing attention to the absence
of a value in a table.
foreign key (FK)
An attribute or attributes in one table whose values must match the primary key in another table or
whose values must be null. See key.
full functional dependence
A condition in which an attribute is functionally dependent on a composite key but not on any subset
of the key.
functional dependence
Within a relation R, an attribute B is functionally dependent on an attribute A if and only if a given
value of attribute A determines exactly one value of attribute B. The relationship "B is dependent on
A" is equivalent to "A determines B," and is written as A B.
homonyms
The use of the same name to label different attributes. Homonyms generally should be avoided. Some
relational software automatically checks for homonyms and either alerts the user to their existence or
automatically makes the appropriate adjustments. See also synonym.
index
An ordered array of index key values and row ID values (pointers). Indexes are generally used to
speed up and facilitate data retrieval. Also known as an index key.
index key
See index.
inner join
A join operation in which only rows that meet a given criterion are selected. The join criterion can be
an equality condition (natural join or equijoin) or an inequality condition (theta join). The inner join is
the most commonly used type of join. Contrast with outer join.
INTERSECT
In relational algebra, an operator used to yield only the rows that are common to two union-
compatible tables.
