De?ne

a. Integrity constraint
b. Static, as compared with dynamic, integrity constraint
c. Referential integrity
d. Reactive constraint
e. Inclusion dependency
f. Foreign-key constraint

a. An integrity constraint is an application-speci?c restriction on the tuples in one or several relations.
b. Static integrity constraints restrict the legal instances of a database. Examples of static ICs are domain constraints, key constraints, foreign-key constraints, etc. Dynamic integrity constraints restrict the evolution (over time) of legal instances of a database, for instance, a salary increase should not exceed 5%.
c. A referential integrity constraint is a requirement that the referenced tuple must exist.
d. A reactive constraint is a static constraint with a trigger attached. The trigger speci?es what to do if the constraint is violated by an update.
e. An inclusion dependency is a statement “S(¯F) references T(¯K )”, which states that for every tuple s ? s, there is a tuple t ? t that has the same values over the attributes in ¯K as does s over the corresponding attributes in ¯F .
f. A foreign-key constraint is an inclusion dependency in which the set of attributes referred to is a candidate key in the referenced relation.