SQL50道练习题

FROM student s3, (
    SELECT s1.stu_id sid,
        s1.`score` score1,
        s2.`score` score2
    
    FROM score s1, score s2

    WHERE s1.stu_id = s2.stu_id
        AND s1.`course_id` = 1
        AND s2.`course_id` = 2
        AND s1.`score` > s2.`score`) s4
WHERE s3.id = s4.sid;

SELECT
    a.*,
    b.`score` score1,
    c.`score` score2
FROM
        student a
JOIN     score b
    ON a.`id`=b.`stu_id`
JOIN    score c
    ON b.course_id = 1 
    AND c.`course_id`=2 
    AND a.`id`=c.`stu_id` 
    AND b.`score`>c.`score`;