Database Concept-Formal Relational Query Language Exercises

6.10 Using the university model, use relational algebra to express the following query.

.  Find all students who have taken at least one computer (Comp. Sol) course.  ',.  Find out the IDs and names of all students who did not take any courses before the spring of 2009.  c For each department, find the best salary for teachers in that department.  It can be assumed that each department has at least one teacher.  d On the basis of finding the highest salary of each department in the previous question, find the minimum salary of the highest salary of all departments.

University model map

Insert picture description here

answer:

Insert picture description here

6.11

Insert picture description here

Relational database (Figure 6-22)

Insert picture description here

answer

Detailed explanation of division operation
Insert picture description here

6.14

topic

Insert picture description here

answer

Insert picture description here

6.15

topic

Insert picture description here
Insert picture description here

Relational database (Figure 6-22)

Insert picture description here

answer

Insert picture description here
Insert picture description here
Insert picture description here

Guess you like

Origin blog.csdn.net/joey_ro/article/details/108196114