sqlString = "select planTerm_Year,courseName,teacherID,classDate,classLessons,classAdd from tCourses,tArrCourses where tArrCourses.classID =( where classID =(select classID from tStudents where tStudents.stuID='" + userID + "'))AND tArrCourses.courseID=tCourses.courseID AND tArrCourses.teacherID=tCourses.teacherID";
sqlString = "select planTerm_Year,courseName,teacherID,classDate,classLessons,classAdd
from tCourses,tArrCourses
where tArrCourses.classID =(select classID from tStudents where tStudents.stuID='" + userID + "')
AND tArrCourses.courseID=tCourses.courseID
AND tArrCourses.teacherID=tCourses.teacherID";
select planTerm_Year,courseName,teacherID,classDate,classLessons,classAdd
from tCourses,tArrCourses
where tArrCourses.classID =
(select classID from tStudents where tStudents.stuID='" + userID + "')
AND tArrCourses.courseID=tCourses.courseID
AND tArrCourses.teacherID=tCourses.teacherID";
应该用
tArrCourses.classID in