Following table has two attributes Employee_ID and Manager_id, where Employee_id is a primary key and Manager_id is a foreign key referencing Employee_id with on-delete cascade: Employee_id Manager_id 20 40 25 40 30 35 35 20 40 45 45 25 On deleting the table (20,40), the set of other tuples that must be deleted to maintain the referential integrity of table is
(30,35) and (35,20) only
Deleting employee 20 deletes the referencing row (35,20). Deleting employee 35 then deletes (30,35). No row references employee 30, so the cascade stops; the other deleted tuples are (35,20) and (30,35).
Important Questions from Relational Model
Given the relational schema $R = (U,V,W, X, Y, Z)$ and the set of functional dependencies: $$\{U \rightarrow V, U \rightarrow W, WX \rightarrow Y, WX \rightarrow Z, V \rightarrow X\}$$ Which of the following functional dependencies can be derived from the above set?
- The ‘12 Rules for Relational Database’ were given by
- Which of the following statement(s) is/are FALSE in the context of Relational DBMS ?
I. Views in a database system are important because they help with access control by allowing users to see only a particular subset of the data in the database.
II. E-R diagrams are useful to logically model concepts.
III. An update anomaly is when it is not possible to store information unless some other, unrelated information is stored as well.
IV. SQL is a procedural language. - Let $R(A,B,C,D,E)$ be a relational schema with functional dependency set $F=\{A\rightarrow BC,\ CD\rightarrow E,\ E\rightarrow A\}$.
Which of the following statements is correct? Consider R (A,B,C,D,E) be relation with following dependencies:
C- >F, E- > A, EC- >D, A- >B. Which of the following is a key for R?
