Data Management - Applications 2 Flashcards
Returns a set of records that include what an inner join would return but also includes other rows for which no corresponding match is found in the other table.
??? ??? : A key attribute; that is, an attribute that is part of a key or is the whole key.
outer join / prime attribute
In relational algebra, an operator used to yield all possible pairs of rows from two tables. Also known as the Cartesian product.
an operator used to select a subset of columns.
PRODUCT / PROJECT
Short for relation variable, a variable that holds a relation. A ??? is a container (variable) for holding relation data, not the relation itself.
A detailed system data dictionary that describes all objects in a database.
relvar / system catalog
In a pair of tables to be joined, a join that yields all of the rows in the right table, including the ones with no matching values in the other table. For example, a right outer join of CUSTOMER with AGENT will yield all of the AGENT rows, including the ones that do not have a matching CUSTOMER row
right outer join
A join operator that links tables using an inequality comparison operator (, <=, >=) in the join condition.
In relational algebra, an operator used to merge (append) two tables into a new table, dropping the duplicate rows. The tables must be union-compatible.
theta join / UNION
In ER modeling, a key composed of more than one attribute.
One or more attributes that uniquely identify each entity instance.
composite identifier / identifiers
A relationship in which the primary key of the related entity does not contain a primary key component of the parent entity.
The organization of a relational database as described by the database administrator.
non-identifying relationship / relational schema
An entity that displays existence dependence and inherits the primary key of its parent entity. For example, a DEPENDENT requires the existence of an EMPLOYEE.
A relationship in which the primary key of the related entity does not contain a primary key component of the parent entity.
weak entity / weak relationship
A nested ordering sequence for a set of rows, such as a list in which all last names are alphabetically ordered and, within the last names, all first names are ordered.
cascading order sequence
A SQL aggregate function that outputs the number of rows containing not null values for a given column or expression, sometimes used in conjunction with the DISTINCT clause.
COUNT
