WGU C170 - Data Management – Applications, Exam Review Questions and answers, graded A+. VERIFIED.

WGU C170 - Data Management – Applications, Exam Review Questions and answers, graded A+. VERIFIED. Domain In data modeling, the construct used to organize and describe an attribute's set of possible values. Primary key (PK) 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 One or more attributes that determine other attributes. 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. Determinant Any attribute in a specific row whose value directly determines other values in that row. Dependent An attribute whose value is determined by another attribute. Full functional dependence A condition in which an attribute is functionally dependent on a composite key but not on any subset of the key. Composite key A multiple-attribute key. Key attributes The attributes that form a primary key Superkey An attribute or attributes that uniquely identify each entity in a table. Candidate key A minimal superkey; that is, a key that does not contain a subset of attributes that is itself a superkey. 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. Null The absence of an attribute value. Foreign key 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 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 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 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 Short for relation variable, a variable that holds a relation. It is a container (variable) for holding relation data, not the relation itself.