[Q.66] Which functional dependency X -> Y violates 3NF condition?
In 3NF, for X -> Y, either X must be a super key OR Y must be a prime attribute. If neither holds, 3NF is violated.
[Q.67] What is a 'Foreign Key' in a relational database?
Foreign keys enforce referential integrity across related tables.
[Q.68] Which relational algebra operation extracts specific ROWS from a relation satisfying a predicate?
Selection (sigma) filters tuples (rows) based on a logical condition.
[Q.69] Which relational algebra operation extracts specific COLUMNS from a relation?
Projection (pi) filters attributes (columns) from a relation.
[Q.70] What is 'Dirty Read' anomaly in concurrent database transactions?
Dirty Read occurs when T1 reads uncommitted modifications made by T2 which subsequently rolls back.