SQL 之UPDATE
把“SC”表中“谌燕”老师教的课的成绩都更改为此课程的平均成绩；
UPDATE SC_TIAN A SET(SCORE)=
(SELECT B.A_SCORE
FROM
(SELECT S.CNO,AVG(S.SCORE) AS A_SCORE
FROM SC_TIAN S
JOIN COURSE_TIAN C ON C.CNO=S.CNO
JOIN TEACHER_TIAN T ON T.TNO=C.TNO
WHERE T.TNAME='谌燕'
GROUP BY S.CNO) B
WHERE A.CNO=B.CNO)
WHERE A.CNO IN (
SELECT DISTINCT S.CNO
FROM SC_TIAN S
JOIN COURSE_TIAN C ON C.CNO=S.CNO
JOIN TEACHER_TIAN T ON T.TNO=C.TNO
还没人转发这篇日记
