CSCI-SHU MISC Introduction to Programming and Problem Solving | New York University

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NYU – TANDON SCHOOL OF ENGINEERING CS-GY 6083 - B, FALL 2019 Principles of Database Systems

Assignment: 4 [100 points , 5% weightage] Please submit your assignment on NYU class with PDF document attachment. Please mention Student ID, Name, Course, Section Number, and date of submission on first page of your submission. Insert picture of result screenshots in same PDF document.

NO LATE SUBMISSION or RESUBMISSION WILL BE ALLOWED. DO NOT WAIT UNTIL LAST DAY OF SUBMISSION DEADLINE, CHECK DUE DATE CAREFULLY, AND CHECK YOUR SUBMISSION TH0ROUGHLY BEFORE SUBMITTING.

Q1: 30 points Consider the instructor relation shown in following Figure 1. [30] a) Construct a bitmap index on the attribute SALARY, dividing salary values into 4 ranges: below 50000, 50000 to below 60000, 60000 to below 70000, and 70000 and above. b) Construct a bitmap index on the attribute DEPARTMENT c) Consider a query that requests all instructors in the Finance department with salary of 80000 or more.

Show intermediate and final bitmaps constructed to answer the query, and provide NAME, and SALARY of qualified instructors for the given query.

Submit picture of Bitmap created for a, b, and c, and final resulting bitmap to answer the query.

ID

NAME

DEPARTMENT

SALARY

Figure 1.

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a) Bitmap Index on Salary range is: SALARY RANGE AS BELOW S1: 0 to 49000 S2: 50000 to 59000 S3: 60000 to 69000 S4: 70000 and more Bitmap Index on Salary range is:

b) Bitmap Index on Department is:

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c) Intermediate and final result using Bitmap on Salary Range and Department, for the given query.

To find all instructors in the Finance department with salary of 80000 or more, we first find the intersection of the Finance department bitmap and S4 bitmap of salary and then scan on these records for salary of 80000 or more.

Intersection (AND logic) of Finance department bitmap and S4 bitmap of salary

Scan on these records with salary 80000 or more gives Wu and Singh as the instructors who satisfy the given query.

Q2: 20 points Consider relational model of a project organization as depicted in Figure 2.

Figure 2.

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Consider that there are 80,000 employees with 15 different job functions, working in 20 various departments for total 90 projects.

Following query is being frequently used by the business.

To find employee names, their department name, Salary, and the name of the project assigned to employees for given department and the job function. a) Create appropriate indices to support faster query processing. Submit DDL code for creating such indices.

CREATE BITMAP INDEX IDX_DEPTNO ON AP_EMP(DEPTNO); CREATE BITMAP INDEX IDX_JOB ON AP_EMP(JOB);

b) Write the SQL query in question and justify your answer for the type of indices you have created and for columns those indices are created. Submit your explanation about choice of index type, and columns.

SELECT a.empno, a.ename, a. sal, a.job,a.deptno, b.dname, d.pname FROM emp a JOIN dept b on a.deptno=b.deptno JOIN proemp c ON a.empno=c.empno JOIN project d on c.projid=d.projid WHERE job='ANALYST' AND a.deptno=20; Above is the possible SQL query to answer the query for given department and job (example with Job as ANALYST and department number as 20 Since columns ‘job’ and ‘deptno’ are in filter condition, they are good choice for creating indexes for faster access of qualifying records.

Since ‘job’ and ‘deptno’ are having few distinct values as compared to total number of records in ‘emp’ table, they are good fit for BITMAP index.

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Q3: 50 points Consider relational model of a project organization as depicted in Figure 2.

Write SQL queries for following questions. a) For each job, list two highest earning employees name, their job, and salary.

SELECT * FROM (SELECT empno, ename, job, sal , RANK() OVER (PARTITION BY JOB ORDER BY sal desc ) AS myrank FROM emp) WHERE myrank <= 2;

b) List employee’s name, job, and salary along with highest and lowest salary of their respective job SELECT ename, job, sal, MIN(sal) KEEP (DENSE_RANK FIRST ORDER BY sal) OVER (PARTITION BY job) AS lowestsal, MAX(sal) KEEP (DENSE_RANK LAST ORDER BY sal) OVER (PARTITION BY job) AS highestsal FROM emp ORDER BY job, sal;

c) List employee number, name of the employee, and number of projects who has worked the highest number of projects WITH PROJCNTRANK AS ( select empno,count(projid) cnt, rank () over (order by count(projid) desc) as myrank from proemp group by empno ) SELECT A.EMPNO, A.ENAME, B.CNT, B.MYRANK FROM EMP A JOIN PROJCNTRANK B ON A.EMPNO=B.EMPNO AND MYRANK<2;

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d) List employees name who have at least one employee reporting to them SELECT a.empno,a.deptno, a.sal FROM emp a WHERE EXISTS (SELECT 1 FROM emp b WHERE b.mgr=a.empno);

e) List department wise total salary for those departments which has total salary more than that of department at NEW YORK SELECT deptno, sum(sal) FROM emp GROUP BY deptno HAVING sum(sal)>(select sum(sal) from emp where deptno=(select deptno from dept where loc='NEW YORK'));

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