Domain Correct Answer: In data modeling, the construct used to organize and describe an attribute's set of possible values.
Primary key (PK) Correct Answer: An identifier composed of one or more attributes that uniquely identifies a row. Also, a candidate key selected as a unique entity identi...
WGU C170 - Data Management - Applications
Domain Correct Answer: In data modeling, the construct used to organize and describe an
attribute's set of possible values.
Primary key (PK) Correct Answer: An identifier composed of one or more attributes that
uniquely identifies a row. Also, a candidate key selected as a unique entity identifier. A minimal
superkey.
Key Correct Answer: One or more attributes that determine other attributes.
Determination Correct Answer: 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.
Determinant Correct Answer: Any attribute in a specific row whose value directly determines
other values in that row.
Dependent Correct Answer: An attribute whose value is determined by another attribute.
Full functional dependence Correct Answer: A condition in which an attribute is functionally
dependent on a composite key but not on any subset of the key.
Composite key Correct Answer: A multiple-attribute key.
Key attributes Correct Answer: The attributes that form a primary key
Superkey Correct Answer: An attribute or attributes that uniquely identify each entity in a table.
Candidate key Correct Answer: A minimal superkey; that is, a key that does not contain a subset
of attributes that is itself a superkey.
Entity integrity Correct Answer: 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.
Null Correct Answer: The absence of an attribute value.
Foreign key Correct Answer: An attribute or attributes in one table whose values must match the
primary key in another table or whose values must be null.
Referential integrity Correct Answer: A condition by which a dependent table's foreign key
must have either a null entry or a matching entry in the related table.
Secondary key Correct Answer: A key used strictly for data retrieval purposes. For example, the
combination of last name, first name, middle initial, and telephone number will probably match
the appropriate table row. Also called an alternate key.
, Relational algebra Correct Answer: A set of mathematical principles that form the basis for
manipulating relational table contents; the eight main functions are SELECT, PROJECT, JOIN,
INTERSECT, UNION, DIFFERENCE, PRODUCT, and DIVIDE.
Relvar Correct Answer: Short for relation variable, a variable that holds a relation. It is a
container (variable) for holding relation data, not the relation itself.
Closure Correct Answer: A property of relational operators that permits the use of relational
algebra operators on existing tables (relations) to produce new relations.
SELECT operator Correct Answer: An operator used to select a subset of rows. Also known as
RESTRICT.
σ cus_code = 10010
PROJECT operator Correct Answer: An operator used to select a subset of columns. In other
words, it yields a vertical subset of a table. This operation retrieves all rows and some attributes
of a table without using a WHERE clause to limit which rows of the table are included.
π cus_fname, cus_lname
UNION operator Correct Answer: This set operator combines the result set of two or more
SELECT statements, dropping the duplicate rows.
supplier ∪ vendor
Union-compatible Correct Answer: Two or more tables that have the same number of columns
and the corresponding columns have compatible domains.
INTERSECT operator Correct Answer: This set operator combines the output of two SELECT
queries and returns only the rows that appear in both.
supplier ∩ vendor
DIFFERENCE Correct Answer: An operator used to yield all rows from one table that are not
found in another union-compatible table.
supplier - vendor
PRODUCT Correct Answer: An operator used to yield all possible pairs of rows from two
tables.
customer × agent
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