Breast cancer may cause swollen axillary lymph nodes since the lymph vessels of the breast drain into the lymph nodes of the armpit. These nodes become enlarged when cancer cells spread beyond the breast tissue.
Relational database. (Redirected from Database constraints) A relational database is a digital database whose organization is based on the relational model of data, as proposed by E. F. Codd in 1970. The various software systems used to maintain relational databases are known as a relational database management system (RDBMS).
A constraint is a statement of restriction that modifies a requirement or set of requirements by limiting the range of acceptable solutions. While this may initially be perceived as a drawback to the development of a project, constraints in many ways have a powerful way of helping projects work smoothly or reduce the risks of catastrophic failure. Constraints appear across all levels of the requirements hierarchy (business, functional, system, user).