BMGT 402 Lecture Notes - Lecture 5: Referential Integrity, Unique Key, Data Definition Language

• School: University of Maryland
• Department: Business and Management
• Course: BMGT 402
• Professor: Woei- Jyh Lee

Document Summary

Integrity enhancement features: consider five types of integrity constraints. Check (searchcondition: sex char not null check (sex in ( m", "f")) [default defaultoption][check(searchcondition)]: create domain sextype as char, default m" check (value in ( m", f")), sex sextype not null searchcondition can involve a table lookup, create domain branchno as char(4, check (value in (select branchno from. Domains can be removed: drop domain domainname [restrict | Primary key (pk) of a table must contain a unique, non-null value for each row. Iso standard supports definition of pk with priamry key clause in create table and alter table statements: primary key (propertyno, primary key (clientno propertyno) Can only have one primary key clause per table but can still ensure uniqueness for alternate keys (aks) using. Foreign key (fk) is column or set of columns that links each row in child table containing fk to row of parent table containing matching pk|ak.