INFO232 - CH 3

________ Composed of more than one attribute

• Composite key

• Key attribute

• key

• Candidate key

________  Any attribute that is part of a key

• Composite key

• Key attribute

• key

• Candidate key

_______ A superkey without unnecessary attributes

• Composite key

• Key attribute

• key

• Candidate key

________ Any key that uniquely identifies each row

• Composite key

• Key attribute

• key

• super key

Designers use flags to avoid nulls

• true

• false

(unique and no null) All Primary key entries

• Entity integrity

• REFERENTIAL INTEGRITY

(null or matching) - A Foreign key may have either a null

• Entity integrity

• REFERENTIAL INTEGRITY

yields values for all rows found in a table.

• SELECT

• UNION

• INTERSECTION

• PROJECT

combines all rows from two tables, excluding duplicate rows.

• SELECT

• UNION

• INTERSECTION

• PROJECT

yields all values for selected attributes

• SELECT

• UNION

• INTERSECTION

• PROJECT