WGU C170 CH 1 WITH COMPLETE SOLUTIONS 100% VERIFIED!!
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.
index - ANSWER>>A sorted array of index key values and row ID values (pointers).
Indexes are normally created to accelerate and ease data access. Also called an index
key.
index key - ANSWER>>Synonym for index
inner join The join operation where only those rows that satisfy the given condition or
criterion are retrieved. The inner join criteria include an equality relationship, referred
to as either natural join or equijoin and inequality relationship as theta join. Inner join is
the most used type of join. Contrast with outer join.
INTERSECT - ANSWER>>In relational algebra, an operator used to return only the
rows common to two union-compatible tables.
JOIN - ANSWER>>In relational algebra, a type of operator used to return rows from
two tables based on criteria. There are several types of join including natural join, theta
join, equijoin and outer join.
join columns Columns that are participants in join operations. Such columns joined
generally possess the same or similar values that is a compatible domain
key An attribute, possibly composite, through which other attributes are identified.
Syn: see also superkey, candidate key, primary key PK, secondary key, foreign key
, key attribute An attributes those comprising a prime attributes. See prime attribute
left outer join - ANSWER>>In a pair of tables to be joined, a join that returns all the
rows in the left table, even if there are no matching values in the other table. For
example, a left outer join of CUSTOMER with AGENT will return all of the CUSTOMER
rows, even those that do not have a matching AGENT row. See also outer join and right
outer join.
linking table - ANSWER>>In the relational model, a table that implements an M:M
relationship. See also composite entity.
natural join - ANSWER>>A relational operation that yields a new table composed of
only the rows with common values in their common attribute(s).
null - ANSWER>>The absence of an attribute value. Note that a null is not a blank.
outer join ANSWER >>A relational algebra join operation that produces a table in
which all unmatched pairs are retained; unmatched values in the related table are left
null. Contrast with inner join.
predicate logic ANSWER >>Used extensively in mathematics to provide a framework in
which an assertion (statement of fact) can be verified as either true or false.
primary key (PK) - ANSWER>>In the relational model, an identifier comprising one or
more attributes that uniquely identifies a row. Also, a candidate key chosen as unique
identifier of an entity. See also key.
prime attribute - ANSWER>>A key attribute; that is, an attribute which is part of a key
or is the whole key.
PRODUCT - ANSWER>>in relational algebra, an operator that returns all possible pairs
of rows from two tables. Also called the Cartesian product
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.
index - ANSWER>>A sorted array of index key values and row ID values (pointers).
Indexes are normally created to accelerate and ease data access. Also called an index
key.
index key - ANSWER>>Synonym for index
inner join The join operation where only those rows that satisfy the given condition or
criterion are retrieved. The inner join criteria include an equality relationship, referred
to as either natural join or equijoin and inequality relationship as theta join. Inner join is
the most used type of join. Contrast with outer join.
INTERSECT - ANSWER>>In relational algebra, an operator used to return only the
rows common to two union-compatible tables.
JOIN - ANSWER>>In relational algebra, a type of operator used to return rows from
two tables based on criteria. There are several types of join including natural join, theta
join, equijoin and outer join.
join columns Columns that are participants in join operations. Such columns joined
generally possess the same or similar values that is a compatible domain
key An attribute, possibly composite, through which other attributes are identified.
Syn: see also superkey, candidate key, primary key PK, secondary key, foreign key
, key attribute An attributes those comprising a prime attributes. See prime attribute
left outer join - ANSWER>>In a pair of tables to be joined, a join that returns all the
rows in the left table, even if there are no matching values in the other table. For
example, a left outer join of CUSTOMER with AGENT will return all of the CUSTOMER
rows, even those that do not have a matching AGENT row. See also outer join and right
outer join.
linking table - ANSWER>>In the relational model, a table that implements an M:M
relationship. See also composite entity.
natural join - ANSWER>>A relational operation that yields a new table composed of
only the rows with common values in their common attribute(s).
null - ANSWER>>The absence of an attribute value. Note that a null is not a blank.
outer join ANSWER >>A relational algebra join operation that produces a table in
which all unmatched pairs are retained; unmatched values in the related table are left
null. Contrast with inner join.
predicate logic ANSWER >>Used extensively in mathematics to provide a framework in
which an assertion (statement of fact) can be verified as either true or false.
primary key (PK) - ANSWER>>In the relational model, an identifier comprising one or
more attributes that uniquely identifies a row. Also, a candidate key chosen as unique
identifier of an entity. See also key.
prime attribute - ANSWER>>A key attribute; that is, an attribute which is part of a key
or is the whole key.
PRODUCT - ANSWER>>in relational algebra, an operator that returns all possible pairs
of rows from two tables. Also called the Cartesian product
