[英]Stuck on fixing this query, mistakes in two commands that I wrote
EMPLOYEE (fname, minit, lname, ssn, birthdate, address, sex, salary, superssn, dno)
KEY: ssn
DEPARTMENT (dname, dnumber, mgrssn, mgrstartdate)
KEY: dnumber.
PROJECT (pname, pnumber, plocation, dnum)
KEY: pnumber.
WORKS_ON (essn, pno, hours)
KEY: (essn, pno)
DEPENDENT (essn, dependent-name, sex, bdate, relationship)
KEY: (essn, dependent-name)
So I'm just really confused by how do I add more materials to the select command, let's say add SSN 因此,我对如何向select命令添加更多材料感到非常困惑,比如说添加SSN
I want to find the last name and first name of all the managers who is on project number 47: 我想找到项目编号为47的所有经理的姓氏和名字:
SELECT lname, fname
FROM employee e, department d
Where d.mgrssn = e.ssn
WHERE e.ssn IN (SELECT w.essn
FROM works_on w, project p
WHERE w.pno = p.pnumber
AND w.pno ='47'
);
But now I want add ssn to it: 但是现在我想添加ssn:
SELECT lname, fname, ssn
FROM employee e, department d
Where d.mgrssn = e.ssn
WHERE ssn IN (SELECT w.essn
FROM works_on w, project p
WHERE w.pno = p.pnumber
AND w.pno ='02'
);
Could you try this? 你可以试试这个吗?
select * from employee e,works_on w,department d
where e.ssn=d.mgrssn and e.ssn=w.essn and w.pno = 47
edit using joins 使用联接进行编辑
select * from employee
join works_on on employee.ssn=works_on.essn
join department on employee.ssn=department.mgsrssn
wher works_on.pno=47
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