give the query script or the relational algebra expression. Question: 4. Find the projects that belong to the department with DNO=1 or 2 or 3
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There is a Company Database that manages the data of employee, department and project. The relational schemas are as follows:
EMPLOYEE (Fname, Lname, Employee_id, Gender, Salary, DNO). The attribute means: First name, Last name, employee id, gender, salary, the department number in which the employee works. Each employee has a unique employee id, and can join in projects that in different department.
DEPARTMENT (DNO, Dname, Manager_id, Dlocation). The attribute means: Department number, department name, department manager id, department location. The department manager is a type of the employee, thus the Manager_id is a foreign key that references the Employee_id in EMPLOYEE table.
PROJECT (Project_NO, Pname, DNO). The attribute means: project number, project name, department number of the department that the project belongs to.
Part of the data in the relations are as follows：
Table1 EMPLOYEE
|
Fname |
Lname |
Employee_id |
Gender |
Salary |
DNO |
|
John |
Smith |
20182101 |
Male |
40000 |
2 |
|
Franklin |
Wong |
20182102 |
Male |
50000 |
1 |
|
Jennifer |
Wallace |
20183101 |
Female |
35000 |
3 |
|
Joyce |
Clinton |
20183102 |
Female |
28000 |
3 |
|
Peter |
Bush |
20184101 |
Male |
33000 |
4 |
Table 2 DEPARTMENT
|
DNO |
Dname |
Manager_id |
Dlocation |
|
1 |
Research |
20181105 |
Stanford |
|
2 |
Technology |
20182102 |
Houston |
|
3 |
Service |
20183101 |
Houston |
|
4 |
Administration |
20184101 |
Stanford |
Table 3 PROJECT
|
Project_NO |
Pname |
DNO |
|
1001 |
TransportationMap |
1 |
|
1002 |
TwitterFriendship |
1 |
|
1003 |
PowerSystem |
1 |
|
2001 |
Python |
2 |
|
2002 |
Parallel |
2 |
|
3001 |
Customer |
3 |
Based on the above relational schema, please write the SQL scripts to do the question - 4. Notes: you do not need to give the query results. You only need to give the query script or the relational algebra expression.
Question:
4. Find the projects that belong to the department with DNO=1 or 2 or 3
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