1
Update operations in RDBMS are categorized into INSERT, DELETE, and MODIFY (UPDATE).
2
INSERT operations can violate four main constraints: Domain constraints (data type mismatch), Key constraints (duplicate primary keys), Entity integrity (null primary keys), and Referential integrity (invalid foreign keys).
3
When a constraint is violated during an INSERT, the default DBMS action is typically to reject the operation, though it may prompt the user to correct the data or insert missing referenced records.
4
DELETE operations primarily risk violating referential integrity if the deleted tuple is referenced by foreign keys in other relations.
5
Strategies for handling DELETE violations include rejecting the deletion or using 'cascade' (propagating the deletion to related records).
6
MODIFY (UPDATE) operations involve changing existing attribute values and can trigger multiple violations simultaneously, such as key constraint violations (if updating a primary key to an existing value) or referential integrity violations (if updating a foreign key to a non-existent value).