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WGU C170 - Data Management - Applications With Complete Solutions Latest Update
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WGU C170 - Data Management - Applications With Complete Solutions Latest Update
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WGU C170 - Data Management -Applications With Complete Solutions Latest
Update
Domain - correct answers In data modeling, the construct used to organize and
describe an attribute's set of possible values.
Primary key (PK) - correct answers 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 answers One or more attributes that determine other attributes.
Determination - correct answers 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 answers Any attribute in a specific row whose value directly
determines other values in that row.
Dependent - correct answers An attribute whose value is determined by another
attribute.
Full functional dependence - correct answers A condition in which an attribute is
functionally dependent on a composite key but not on any subset of the key.
,Composite key - correct answers A multiple-attribute key.
Key attributes - correct answers The attributes that form a primary key
Superkey - correct answers An attribute or attributes that uniquely identify each
entity in a table.
Candidate key - correct answers A minimal superkey; that is, a key that does not
contain a subset of attributes that is itself a superkey.
Entity integrity - correct answers 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 answers The absence of an attribute value.
Foreign key - correct answers 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 answers 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 answers 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 answers 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 answers 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 answers A property of relational operators that permits the use
of relational algebra operators on existing tables (relations) to produce new
relations.
SELECT operator - correct answers An operator used to select a subset of rows.
Also known as RESTRICT.
σ cus_code = 10010
PROJECT operator - correct answers 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 answers This set operator combines the result set of
two or more SELECT statements, dropping the duplicate rows.
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