WGU C170 - DATA MANAGEMENT – APPLICATION QUESTIONS WITH THE CORRECT ANSWERS UPDATED

WGU C170 - Data Management - Applications
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WGU C170 - DATA MANAGEMENT – APPLICATION QUESTIONS WITH THE
CORRECT ANSWERS UPDATED




1.Domain: In data modeling, the construct used to organize and descr
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ibe an attribute's set of possible values.
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2.Primary key (PK): An identifier composed of one or more attributes that u
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niquely identifies a row. Also, a candidate key selected as a unique entity id
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entifier. A minimal superkey. n n n


3.Key: One or more attributes that determine other attributes.
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4.Determination: The role of a key. In the context of a database table, the sta n n n n n n n n n n n n n n


tement "A determines B" indicates that knowing the value of attribute A me
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ans that the value of attribute B can be looked up.
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5.Determinant: Any attribute in a specific row whose value directly deter n n n n n n n n n n


mines other values in that row.
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6.Dependent: An attribute whose value is determined by another attribute.
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7.Full functional dependence: A condition in which an attribute is functio
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nally dependent on a composite key but not on any subset of the key.
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8.Composite key: A multiple-attribute key. n n n n


9.Key attributes: The attributes that form a primary key
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10.Superkey: An attribute or attributes that uniquely identify each entity in
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a table. n


11.Candidate key: A minimal superkey; that is, a key that does not contain a
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nsubset of attributes that is itself a superkey.
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12.Entity integrity: The property of a relational table that guarantees each
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entity has a unique value in a primary key and that the key has no null val
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ues.
13.Null: The absence of an attribute value.
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14.Foreign key: An attribute or attributes in one table whose values must m
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atch the primary key in another table or whose values must be null.
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15.Referential integrity: A condition by which a dependent table's foreign ke
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, WGU C170 - Data Management - Applications
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y must have either a null entry or a matching entry in the related table.
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16.Secondary key: A key used strictly for data retrieval purposes. For exa
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mple, the combination of last name, first name, middle initial, and teleph
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one number will probably match the appropriate table row. Also called an
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alternate key. n


17.Relational algebra: A set of mathematical principles that form the basis f
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or ma- n


nipulating relational table contents; the eight main functions are SELECT, P
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ROJECT, JOIN, INTERSECT, UNION, DIFFERENCE, PRODUCT, and DIVIDE.
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18.Relvar: Short for relation variable, a variable that holds a relation. It is a c
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ontainer (variable) for holding relation data, not the relation itself.
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19.Closure: A property of relational operators that permits the use of rel
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ational algebra operators on existing tables (relations) to produce new r
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elations.
20.SELECT operator: An operator used to select a subset of rows. Also kno
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wn as RESTRICT.
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, WGU C170 - Data Management - Applications
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Ãcus_code = 10010 n n


21.PROJECT operator: An operator used to select a subset of columns. In ot n n n n n n n n n n n n


her words, it yields a vertical subset of a table. This operation retrieves all r
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ows and some attributes of a table without using a WHERE clause
n n s ofto
the tabl
limit w n n n n n n n n n n n n n n n


hich row n e
are included. n




Àcus_fname, cus_lname n


22.UNION operator: This set operator combines the result set of two or
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more SELECT statements, dropping the duplicate rows.
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supplier * vendor n n


23.Union-
compatible: Two or more tables that have the same number of columns an
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d the corresponding columns have compatible domains.
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24.INTERSECT operator: This set operator combines the output of two SEL n n n n n n n n n n


ECT queries and returns only the rows that appear in both.
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supplier ) vendor n n


25.DIFFERENCE: An operator used to yield all rows from one table that a n n n n n n n n n n n n


re not found in another union-compatible table.
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supplier - vendor n n


26.PRODUCT: An operator used to yield all possible pairs of rows from two t n n n n n n n n n n n n n


ables.

customer × agent n n


27.JOIN: In relational algebra, a type of operator used to yield rows from tw
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o tables based on criteria. There are many types, such as natural, theta, eq
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ui, and outer. n n


28.Natural join (JOIN): A relational operation that yields a new table compo
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sed of only the rows with common values in their common attribute(s).
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customer agent
29.Equijoin: A join operator that links tables based on an equality conditi
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on that compares specified columns of the tables. Is a special type of the
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ta join n


30.Theta join: A join operator that links tables using an inequality comp
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