Homework 2, Relational Algebra H Instructions: Hand-written answers are acceptab

Question

Homework 2, Relational Algebra H Instructions: Hand-written answers are acceptable. Be clear and to the point. According to the four tables in the following, use appropriate relational algebra to derive the answers. EMPLOYEES PLANS ECode EName 101 Andy 102 Betty 103 Cindy 104 David 105 Ellen PCodePDesc 25 14 17 Term Life Stock Option Long-Term Disability Dental Insurance JOBS BENEFIT PCode Faculty Staff Administrator 101 101 102 102 102 103 103 105 2 Write step-by-step relational algebra to find... I. ECode and EName of employees whose job description are 'Staff with over 20 years of service. 2. ECode and EName of employees of employees who have 'Dental Insurance' benefit. 3. ECode and EName of employees whose job description is Staff and who has 'Stock Option' benefit. 4. ECode of employee(s) who do NOT have any benefit plan.

Explanation / Answer

1)

here its first Jcode=2 and over 20 yrs of service we got Ecode=101 and Ename = Andy.

2)

here we have Pcode=4, we get Ecode=102 Ename= Betty and Ecode=103 with Ename=Cindy.

3)

employees with Jcode=2 and Pcode=2 are

only

Ecode=101

with Ename=andy.

4)

Ecode of employees with out any benefit plan are

Ecode=104 (employee without any Pcode).

Note :- have any doubt ?? ask in comments !! :)

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