CS计算机代考程序代写 database CS3402 Database Systems CS3402 Tutorial 5:

CS3402 Database Systems CS3402 Tutorial 5:
1. Answer:
(a) T1 × T2
Tutorials
P
Q
R1
A
B
R2
10
a
5
10
b
6
10
a
5
25
c
3
10
a
5
10
b
5
15
b
8
10
b
6
15
b
8
25
c
3
15
b
8
10
b
5
25
a
6
10
b
6
25
a
6
25
c
3
25
a
6
10
b
5
(b) T1 ⋈􏰁􏰂.􏰃􏰄􏰁􏰅.􏰆T2
(c) T1 ⋈􏰁􏰂.􏰇􏰄􏰁􏰅.􏰈T2
(d) T1 ⋈􏰁􏰂.􏰉􏰊􏰁􏰅.􏰉T2
P
Q
R1
A
B
R2
10
a
5
10
b
6
10
a
5
10
b
5
25
a
6
25
c
3
P
Q
R1
A
B
R2
15
b
8
10
b
6
15
b
8
10
b
5
P
Q
R1
A
B
R2
15
b
8
10
b
6
15
b
8
25
c
3
15
b
8
10
b
5
25
a
6
25
c
3
25
a
6
10
b
5
10
a
5
25
c
3
(e) T1 ∗ T2
P
Q
R
A
B
10
a
5
10
b
25
a
6
10
b

CS3402 Database Systems Tutorials
2. Answer:
(a) Find the SSn (social security number) of all employees who are not supervisors
𝜋􏰋􏰋􏰌 (EMPLOYEE) − 𝜋 􏰍􏰎􏰏􏰐􏰑_􏰋􏰋􏰌 (EMPLOYEE)
(b) Find the SSn of all employees who either work in department 5 or directly
supervise an employee who works in department 5
𝜋􏰍􏰋􏰌 (𝜎􏰒􏰌􏰓􏰄􏰔 (EMPLOYEE)) ∪ 𝜋􏰍􏰎􏰏􏰐􏰑_􏰋􏰋􏰌 (𝜎􏰒􏰌􏰓􏰄 (EMPLOYEE))
(c) List the names and numbers of all departments locating in ‘Houston’
𝜋􏰒􏰌􏰕􏰖􏰐,􏰒􏰌􏰎􏰖􏰗􏰐􏰑 (𝜎􏰒􏰘􏰓􏰙􏰕􏰚􏰛􏰓􏰌􏰄􏰜􏰝􏰓􏰎􏰋􏰚􏰓􏰌􏰜 (DEPARTMENT ∗ DEPT_LOCATIONS) )
(d) List the first names of all employees who have a dependent with the same first name as themselves
𝜋􏰞􏰌􏰕􏰖􏰐 (EMPLOYEE ⋈􏰍􏰋􏰌􏰄􏰟􏰋􏰋􏰌 𝐀𝐍𝐃 􏰞􏰌􏰕􏰖􏰐􏰄􏰒􏰐􏰏􏰐􏰌􏰠􏰐 _􏰌􏰕􏰖􏰐 DEPENDENT))
(e) Retrieve the salary of all employees in department 5 who work more than 10 hours per week on the project named ‘ProjectX’
WORK510 ← WORKS_ON ⋈􏰃􏰌􏰎􏰖􏰗􏰐􏰑􏰄􏰃􏰌􏰓 𝐀𝐍𝐃 􏰒􏰌􏰎􏰖􏰄􏰔 𝐀𝐍𝐃 􏰝􏰓􏰎􏰑􏰋􏰊􏰂􏰡 PROJECT
PROJECTX510 ← 𝜎􏰃􏰌􏰕􏰖􏰐􏰄􏰜􏰃􏰑􏰓􏰢 (WORK510) 𝜋􏰍􏰕􏰘􏰕􏰑􏰣 (PROJECTX510 ⋈􏰟􏰋􏰋􏰌􏰄􏰍􏰋􏰌EMPLOYEE)