- 查询学习课程”python”比课程 “java” 成绩高的学生的学号;
– 思路：
– 获取所有有python课程的人（学号，成绩） - 临时表
– 获取所有有java课程的人（学号，成绩） - 临时表
– 根据学号连接两个临时表：
– 学号 | 物理成绩 | 生物成绩
– 然后再进行筛选1
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5select A.s_id from
(select s_id, num as python from score left join course on score.c_id = course.c_id where course.c_name = 'python') as A
left join
(select s_id, num as java from score left join course on score.c_id = course.c_id where course.c_name = 'java') as B
on A.s_id = B.s_id where A.python > B.java;
查询平均成绩大于65分的同学的姓名和平均成绩(保留两位小数);
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5SELECT student.s_name as names, round(AVG(score.num), 2) as average
FROM student, score
WHERE student.s_id = score.s_id
GROUP BY student.s_name
HAVING AVG(score.num) > 65;查询所有同学的姓名、选课数、总成绩
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5SELECT student.s_name, COUNT(score.s_id) as course_num, SUM(score.num) as total_grades
FROM student, score
WHERE student.s_id = score.s_id
GROUP BY student.s_name
ORDER BY student.s_name;查询所有的课程的名称以及对应的任课老师姓名;
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3SELECT course.c_name, teacher.t_name
FROM course, teacher
WHERE course.t_id = teacher.t_id;查询没学过“alex”老师课的同学的姓名;
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7SELECT s_name
FROM student
WHERE student.s_id NOT IN (
SELECT DISTINCT score.s_id
FROM score, course, teacher
WHERE course.c_id = score.c_id AND teacher.t_id = course.t_id AND teacher.t_name = 'alex'
)查询学过’python’并且也学过编号’java’课程的同学的姓名
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7SELECT s_name FROM
(SELECT score.s_id as sid, score.c_id as cid
FROM score, course
WHERE score.c_id = course.c_id AND (course.c_name = 'python' OR course.c_name = 'java')) as B
LEFT JOIN student ON B.sid = student.s_id
GROUP BY s_name
HAVING COUNT(s_name) > 1;查询学过“alex”老师所教的全部课程的同学的姓名
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10SELECT s_name FROM
(SELECT score.s_id as sid, score.c_id as cid
FROM score, course, teacher
WHERE score.c_id = course.c_id AND teacher.t_id = course.t_id AND teacher.t_name = 'alex') as B
LEFT JOIN student ON B.sid = student.s_id
GROUP BY s_name
HAVING COUNT(s_name) = (SELECT COUNT(course.c_id) FROM
course, teacher
WHERE
teacher.t_id = course.t_id AND teacher.t_name='alex');查询挂科超过两门(包括两门)的学生姓名;
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7SELECT s_name FROM
(SELECT score.s_id as sid, score.c_id as 大专栏 SQL语法练习(一)span> cid
FROM score, course
WHERE score.c_id = course.c_id AND (score.num < 60 OR score.num ISNULL)) as B
LEFT JOIN student ON B.sid = student.s_id
GROUP BY s_name
HAVING COUNT(s_name) > 1;查询有课程成绩小于60分的同学的姓名;
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6SELECT s_name FROM
(SELECT score.s_id as sid, score.c_id as cid
FROM score, course
WHERE score.c_id = course.c_id AND score.num < 60) as B
LEFT JOIN student ON B.sid = student.s_id
GROUP BY s_name;查询选修了全部课程的学生姓名;
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14SELECT s_name FROM
(SELECT score.s_id as sid, score.c_id as cid
FROM score, course
WHERE score.c_id = course.c_id) as B
LEFT JOIN student ON B.sid = student.s_id
GROUP BY s_name
HAVING COUNT(s_name) = (SELECT COUNT(*) FROM course);
SELECT s_name FROM
student
LEFT JOIN score ON student.s_id = score.s_id
GROUP BY s_name
HAVING COUNT(s_name) = (SELECT COUNT(*) FROM course)查询至少有一门课程与“貂蝉”同学所学课程相同的同学姓名；
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6SELECT s_name
FROM student, score
WHERE student.s_id = score.s_id AND student.s_name != '貂蝉' AND score.c_id IN (SELECT c_id FROM score, student
WHERE score.s_id = student.s_id AND student.s_name = '貂蝉')
GROUP BY s_name;查询学过’貂蝉’同学全部课程的其他同学姓名；
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12SELECT s_name FROM
(SELECT score.s_id as sid, score.c_id as cid
FROM score, course, student
WHERE
score.c_id = course.c_id AND
student.s_id = score.s_id AND
student.s_name != '貂蝉' AND
score.c_id in (SELECT c_id FROM score, student WHERE student.s_name = '貂蝉' AND student.s_id = score.s_id)
) as B
LEFT JOIN student ON B.sid = student.s_id
GROUP BY s_name
HAVING COUNT(s_name) >= (SELECT COUNT(score.c_id) FROM score, student WHERE student.s_name = '貂蝉' AND student.s_id = score.s_id);
– ——————————————————————————————————————————————————————————————
– INSERT INTO student VALUES (1, ‘鲁班’, 12, ‘男’);
– INSERT INTO student VALUES (2, ‘貂蝉’, 20, ‘女’);
– INSERT INTO student VALUES (3, ‘刘备’, 35, ‘男’);
– INSERT INTO student VALUES (4, ‘关羽’, 34, ‘男’);
– INSERT INTO student VALUES (5, ‘张飞’, 33, ‘女’);
–
–
– INSERT INTO teacher VALUES (1, ‘大王’);
– INSERT INTO teacher VALUES (2, ‘alex’);
– INSERT INTO teacher VALUES (3, ‘egon’);
– INSERT INTO teacher VALUES (4, ‘peiqi’);
– INSERT INTO course VALUES (1, ‘python’, 1);
– INSERT INTO course VALUES (2, ‘java’, 2);
– INSERT INTO course VALUES (3, ‘linux’, 3);
– INSERT INTO course VALUES (4, ‘go’, 2);
– INSERT INTO score VALUES (1, 1, 1, 79);
– INSERT INTO score VALUES (2, 1, 2, 77);
– INSERT INTO score VALUES (3, 1, 3, 58);
– INSERT INTO score VALUES (4, 2, 2, 66);
– INSERT INTO score VALUES (5, 2, 3, 77);
– INSERT INTO score VALUES (6, 3, 1, 61);
– INSERT INTO score VALUES (7, 3, 2, 64);