A: select a.courseName,count(studentID) from courseTable a ,scTable b where a.courseID = b.courseID group by a.courseName B: select a.studentName,count(courseID) from studentTable a ,scTable b where a.studentID= b.studentID group by a.studentName
select a.courseName,count(studentID) from courseTable a ,scTable b where a.courseID = b.courseID(+) group by a.courseNameselect a.studentName,count(courseID) from studentTable a ,scTable b where a.studentID= b.studentID(+) group by a.studentName 其实就是楼上的,加个左连接严密些。分给楼上吧
select a.courseName,count(studentID)
from courseTable a ,scTable b
where a.courseID = b.courseID
group by a.courseName
B:
select a.studentName,count(courseID)
from studentTable a ,scTable b
where a.studentID= b.studentID
group by a.studentName
from courseTable a ,scTable b
where a.courseID = b.courseID(+)
group by a.courseNameselect a.studentName,count(courseID)
from studentTable a ,scTable b
where a.studentID= b.studentID(+)
group by a.studentName
其实就是楼上的,加个左连接严密些。分给楼上吧