Consider the following relation: r (A1, A2, A3). For all the states of the relation, the result of Query #1 is always the same as that of Query #2. Specify the primary key of the relation r (30 points); Explain why it must be the primary key. Query #1: sr1.A2=r2.A2 Ù r1.A1=r2.A1 (rr1 (r) ´ rr2 (r)) Query #2: select * from r as r1, r as r2 where r1.A1=r2.A1

Q: What are three indications that a surrogate key should be constructed for the primary key of a…

A: Surrogate key is unique key and also called as synthetic primary key. Surrogate key holds anonymous…

Q: Consider the relation schema R (A, B, C, D, E). Find number of super keys if A, CD and BE are the…

A:

Q: For each part of this problem you will need to construct a single SQL query which will check whether…

A: “Since you have posted a question with multiple sub-parts, we will solve first three subparts for…

Q: Given a relation R (A, B), we cannot assign multiple values at column A in a single tuple. True O…

A: Given: Declare true or false.

Q: B.  Draw the digraph of the relation on {a, b, c, d} 1.  {(a, b), (b, b), (b, c), (c, d), (d, a)}…

A: Digraph is a directed graph consists of a set of nodes and set of ordered pairs called edges. Here,…

Q: Solve only 1,2,3 please fast.       Consider the following scheme   Supplier (sid, Sname,…

A: Solution :

Q: (7) Consider the following relation for published books: BOOK (Book_title, Author_name, Book_type,…

A: Here key for the given relation is {BookTitle, Author Name} The FD  BookTitle -> Publisher,…

Q: Consider the following functional dependencies for a relation R(A, B, C, D) A -> (B, C, D), (A, D)…

A: Given relation with functional dependencies is: R(A, B, C, D) A -> (B, C, D), (A, D) -> (B, C)…

Q: Consider a relation T with seven attributes ABCDEFG where AB is a composite primary key for T.…

A: Given the relation relation T with seven attributes ABCDEFG where AB is a composite primary key for…

Q: 1. Given each relation write down the properties that the relation has. If the relation does not…

A: Below is the answer with explanation:

Q: This question is based on the following relation and sample data, where Employee Social Security…

A: Actually, database is a used to stored the data.

Q: Write Queries in Relational Algebra = sleer (r) = From T =where Op(7) Consider the following schema:…

A: Solution:   Given,

Q: Consider the following SQL query on the university schema:          select avg(salary)-(sum(salary)…

A: For numeric values it will always be zero. But when there is a null value the answer will be…

Q: Let R and S be two relations with the following schema: R (P.Q. R1, R2, R3) S (P.Q S1, S2) Where (P,…

A: Let R and S be two relations with the following schema R(P,Q−−−−,R1,R2,R3)R(P,Q_,R1,R2,R3)…

Q: For a relation named X with attributes (A. B, C, D, E, E), where the primary key of X = { A, C, F },…

A: 4NF data base i given below

Q: Consider the following SQL query on the university schema: SELECT AVG(salary) -…

A: The AVG function calculates the AVG of the data by ignoring the null values in it. So, the possible…

Q: Explain three scenarios in which a surrogate key for a relation's primary key should be generated.

A: Introduction Explain three scenarios in which a surrogate key for a relation's primary key should be…

Q: Consider the following relation: Invoice(Order_ID, Order_Date, Customer_ID,…

A: The given relation is not in 3NF as- It contain the transitive dependency in it . Let decompose it…

Q: Part 2: Use the following relations to answer question 4. RO R1 a b b 2 3 4 7 1 2 2 1 2 1 2 3 1 2 4.…

A: a) is join  b) Projection give attributes and union give without duplicates .

Q: We have the following relation: Subscriptions(ID, startingdate, length, customerID, customerName,…

A:

Q: Question 9: The maximum number of superkeys for the relation schema R(E,F,G,H) with E as the key is…

A: The maximum number of superkeys for the relation schema R(E,F,G,H) with E as the key is 8. Option 4…

Q: Question 3. Consider the relation R(ABCD) with AB as a candidate key, choose the FD so that R should…

A: Consider the relation R(ABCD) with AB as a candidate key, choose the FD so that R should be in 2NF…

Q: Consider the relations Courses1, Courses2, LEnrollment and Students. Courses2 name cid AS English…

A: Solution:-) Selection is a relational algebra operation that uses a condition to select rows from a…

Q: Map the car sale ER schema into a relation schema. Specify all primary keys (underline) and foreign…

A:

Q: Consider the following relation:   Invoice(Order_ID, Order_Date, Customer_ID,…

A:

Q: Consider the relations Courses1, Courses2, _Enrollment and Students. Courses cid ename Al Calculus…

A: Write the following query in Relational Algebra. a) Find the sids of students who have enrolled in…

Q: Solve only 4,5,6 . Please fast.   Consider the following scheme Supplier (sid, Sname, rating)…

A: Solution :  Given  Supplier (sid, Sname, rating) Parts (Pid, pname, color) Catalog (sid. Pid, cost)…

Q: What are three criteria that indicate that a surrogate key for a relation's main key should be…

A: Surrogate key: It is a key that does not have any contextual meaning but is used to identify the…

Q: Given the relation R(A, B, C, D, E, F), the following functional dependencies exist: B --> C, D D…

A: Given : R(A, B, C, D, E, F) B --> C, DD --> F

Q: Q7. Consider a database containing two relations: R(A,B,C) and S(D,E,F). For each of three (your…

A: Answer:-

Q: Consider the relation R = {F, T, D, N, S} and the set of functional dependencies K = {F¬D, {D, T}…

A:

Q: Consider the relations Student(name, Marks) and Teacher(ID, name, Salary) in which name is the…

A: Natural join joins two table based on common attribute.

Q: Assume we have two relations R(a,b) and S(b,c). All three attributes (a, b, and c) are integer…

A: Lets see the solution in the next steps

Q: Given the relation schema R(A, B, C) and S(C, D, E), please match each of the following relational…

A: 1-G 1. R U  S === G. (From the given quetion) SELECT * FROM R UNION SELECT * FROM S;

Q: rence relation is defined as 1

A: Given:Solved using divide and conquer approach    nr=n-1r-1+n-1r Function  Xn,r  if  (r=0  or n=r)…

Q: Write a relational algebra expression that is equivalent to the following SQL statement: SELECT…

A: Given SQL statement is, SELECT AVG(SALARY) , COUNT(*) FROM EMPLOYEE WHERE  GENDER = 'M' GROUP BY…

Q: Consider the following parameters of a relation r (A, B, C) in which A be the primary key. nr =…

A: Answer: I have given answered in the handwritten format

Q: Question 10. Consider the relation R (ABCDE) and functional dependencies set {A → B, B → C, C → D, D…

A: In this question 10, we are given a relation R and set of functional dependencies. We are asked the…

Q: Suppose a single relation (table) is used to record the information about students’ enrollment in…

A: Actually, given question regarding normalization.

Q: What is the minimum total number of tuples across all relations that can be entered in the database…

A: Answer One Library book has at least 2 copies. one Library book can be written by one or many…

Q: QUESTION 6 Consider the following functional dependencies for a relation R(A, B, C, D) A -> (B, C,…

A: A super key whose any proper subset is not super key is called candidate key.   closure table : (A)+…

Q: Three instances in which a surrogate key should be constructed for the relation's primary key

A: The following are some of the reasons for creating a surrogate key: When gathering dimensional data…

Q: Consider the relation R = {F, T, D, N, S} and the set of functional dependencies K = {F¬D, {D, T}…

A: Answer : { T , N } is a key of Relation R .

Q: Let R be a relation defined on the set Z by aRb if a <b.

A: Given:

Q: If relation A has 8 rows and 4 attributes and relation B has 4 rows and 4 attributes and the union…

A: Please check the step 2 for solution

Q: TRUE OR FALSE In the Relational Data Model, Referential Integrity Constraint is a special kind/case…

A: Solution: In the Relational Data Model, Referential Integrity Constraint is a special kind/case of…

Q: Consider the following SQL query on the university schema:select avg(salary) - (sum(salary) /…

A: The AVG function calculates the AVG of the data by ignoring the null values in it. So, the possible…

Q: Consider the library database of Figure 3.20. Write the following queries in SQL.Find the average…

A: Explanation: The below query is used to print the average number of books borrowed by the…

Q: Find rollno of students who less than 3 cgpa.

A: 2. Select rollno from Students where cgpa&lt;3 ;