Consider the following SQL query on the university schema:select avg(salary) - (sum(salary) / count(*))from instructorWe might expect that the result of this query is zero since the average of a setof numbers is defined to be the sum of the numbers divided by the number ofnumbers. Indeed this is true for the example instructor relation in Figure 2.1.However, there are other possible instances of that relation for which the resultwould not be zero. Give one such instance, and explain why the result wouldnot be zero.

Q: Consider the given relational schema: Suppliers(sid:integer, sname:string, city:string,…

A: To Do: To choose the correct option.

Q: Q.5 In SQL, foreign key constraints can only reference the primary key attributes of the referenced…

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A: CREATE TRIGGER trg_EMAIL ON EMAIL_CHANGE AFTER INSERT, UPDATE AS IF ( UPDATE (cid, oldemail,…

Q: SQL allows a foreign-key dependency to refer to the same relation, as in the following example:…

A: Answer:-

Q: Consider a database schema with a relation Emp whose attributes are as shownbelow, with types…

A: A schema is a collection of logical structures of data or schema objects. It contains entities and…

Q: Write an SQL query based on the described database for a student exchange program coordinator. To…

A: Introduction:- Below is the complete solution with explanation in detail. Below is the SQL query for…

Q: Consider the bank database of Figure 15.14, where the primary keys are underlined, and the following…

A: Explanation:   The below expression performs the theta join on the smallest amount of data…

Q: Explain why an index is only helpful if an attribute's values are sufficiently diverse.

A: Introduction Use of an index with a wide range of values A file index is a table or other data…

Q: Given the following UML. Transform this model to the database schema. Mark the keys & foreign keys.…

A: According to the information given:- We have to transform this given model to database schema.

Q: 1- Draw an ERD about a restaurant on Oracle SQL developer data modeler, it should contain at least 8…

A: Answer: I have given answered in the handwritten format in brief explanation.

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

A: Solution:   Given,

Q: Consider the given bank database schema given in question (2). Write a SQL trigger to carry out the…

A: The complete answer is given below with explanation.

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: Database Systems For each part of this problem you will need to construct a single SQL query which…

A: Answer is given below

Q: Consider the relation R (A, B, C) with an index on attribute A. a. Give an example of a query that…

A: The answer is as follows.

Q: MPLOYEE FNAME MINIT LNAME SSN BDATE ADDRESS SEX SALARY DNO DEPARTMENT DNAME DNUMBER MGRSSN…

A:

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: For each of the following statements, show whether the statement is correctly executed or not…

A: Keys: In a relational database, keys are extremely important. It is used to uniquely identify any…

Q: Print all the computer sciences courses, these courses with code start with ‘CS’ sorted…

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Q: Consider the relational database of Figure 3.19, where the primary keys areunderlined. Give an…

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

A:

Q: 4. What is the difference between the natural join RS and the theta-join RC S where the condition C…

A:

Q: Testing SQL queries: To test if a query specified in English has been correctlywritten in SQL, the…

A: Reason for using query In the query, select * from teaches natural join instructor; In the above…

Q: Refer the below listed schema diagram to develop the SQL query to display the names of all students…

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Q: Consider the following Relation instance of Students: ID firstNamelastName GPA Address 123 Albertson…

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Q: What will be the result of the following SQL query for the instance of the relation INVENTORY…

A: Introduction :Given , a sql query .we have asked for the result of this query.

Q: Question 3. . Consider the following two command C1 and C2 on the relation R from an SQL database:…

A: DROP TABLE: DROP TABLE statement is used to drop an existing table in a database.  Syntax is  DROP…

Q: Consider the employee database of Figure 3.19. Give an expression in SQL foreach of the following…

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Q: Consider the bank database of Figure 15.14, where the primary keys are underlined, and the following…

A: Justification: The below expression performs theta join on the smallest amount of data possible. It…

Q: Consider the relational database of Figure 3.19, where the primary keys areunderlined. Give an…

A: Solution: Following is the SQL query that gives the name of the each company's whose employees have…

Q: If there are more than one possible candidate keys, provide some instances of relations that have…

A: A candidate key is set of keys which uniquely identifies records. It is possible to have multiple…

Q: Consider the relations: • PROJECT(proj#, proj_name) EMPLOYEE(emp#, emp_name) ASSIGNED(proj#, emp#)…

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Q: Consider the following prolog database: married (logan, marcia), parent (logan, connor), parent…

A: ?- trace. true. [trace] ?- sibling(rosa, julia). Call: (8) sibling(rosa, julia) ? creep…

Q: Consider the following table in a relational database. Last Name Rank Room Shift Smith Manager 234…

A: A candidate key is an attribute or set of attribute which can identify all tuple uniquely.

Q: Consider two relations Order and Product with the schema Order (Oid, Odate, Pid, qty) and Product…

A: Candidate key contain unique and non null values. It uniquely identifies rows in a table. Every…

Q: Although SQL does not support functional dependency constraints, if thedatabase system supports…

A: Given: Although SQL does not support functional dependency constraints, if thedatabase system…

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A: First Normal Form (1NF): =>    If a table includes a composite or multi-valued attribute, it…

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A: QUESTION 1: Find the names of all employees who earn more than every employee of Square Pharma.…

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

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Q: 9. Consider relation schemas and instances given below. In each question below, write a SQL query…

A:

Q: Modify the recursive query in Figure 5.16 to define a relationprereq_depth(course_id, prereq_id,…

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Q: Let T(a,b,c) be a relation in which attribute a is not NULL. Consider the SQL query: SELECT * FROM T…

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A: use of cross and count function in relation algebra

Q: Consider the given schema and answer the questions. Q(a,b), R(b,c), S(b,d), T(b,e). a) For the…

A: Answer: a) i. πa(σc=3(Q ◃▹b=b (R))) ii. πa(Q ◃▹b=b σc=3(R)))

Transaction Processing

Transaction processing is a computational style generally performed by server computers, which supports interactive applications (apps). Transaction processing is also known as information processing, which divides the work into indivisible and individual operations called transactions. The transaction is a set of tasks; a single task is considered as the minimum processing unit that cannot be divided again.