mysql查詢面試一

1. Student(Sid,Sname,Sage,Ssex) 學生表  
2. Course(Cid,Cname,Tid) 課程表  
3. SC(Sid,Cid,score) 成績表  
4. Teacher(Tid,Tname) 教師表   

   SET FOREIGN_KEY_CHECKS=0;
   
   -- ----------------------------
   -- Table structure for course
   -- ----------------------------
   DROP TABLE IF EXISTS `course`;
   CREATE TABLE `course` (
     `Cid` int(11) NOT NULL AUTO_INCREMENT,
     `Cname` varchar(255) DEFAULT NULL,
     `Tid` int(11) DEFAULT NULL,
     PRIMARY KEY (`Cid`),
     KEY `fk_tid` (`Tid`),
     CONSTRAINT `fk_tid` FOREIGN KEY (`Tid`) REFERENCES `teacher` (`Tid`)
   ) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4;
   
   -- ----------------------------
   -- Records of course
   -- ----------------------------
   INSERT INTO `course` VALUES ('1', '001', '1');
   INSERT INTO `course` VALUES ('2', '002', '2');
   INSERT INTO `course` VALUES ('3', '003', '3');
   
   -- ----------------------------
   -- Table structure for sc
   -- ----------------------------
   DROP TABLE IF EXISTS `sc`;
   CREATE TABLE `sc` (
     `id` int(11) NOT NULL AUTO_INCREMENT,
     `Sid` int(11) DEFAULT NULL,
     `Cid` int(11) DEFAULT NULL,
     `score` varchar(50) DEFAULT NULL,
     PRIMARY KEY (`id`),
     KEY `fk_sid` (`Sid`),
     KEY `fk_cid` (`Cid`),
     CONSTRAINT `fk_cid` FOREIGN KEY (`Cid`) REFERENCES `course` (`Cid`),
     CONSTRAINT `fk_sid` FOREIGN KEY (`Sid`) REFERENCES `student` (`Sid`)
   ) ENGINE=InnoDB AUTO_INCREMENT=14 DEFAULT CHARSET=utf8mb4;
   
   -- ----------------------------
   -- Records of sc
   -- ----------------------------
   INSERT INTO `sc` VALUES ('1', '1', '1', '80');
   INSERT INTO `sc` VALUES ('2', '1', '2', '85');
   INSERT INTO `sc` VALUES ('3', '1', '3', '90');
   INSERT INTO `sc` VALUES ('4', '2', '1', '35');
   INSERT INTO `sc` VALUES ('5', '2', '2', '92');
   INSERT INTO `sc` VALUES ('6', '2', '3', '80');
   INSERT INTO `sc` VALUES ('7', '3', '1', '90');
   INSERT INTO `sc` VALUES ('8', '3', '2', '50');
   INSERT INTO `sc` VALUES ('9', '3', '3', '80');
   INSERT INTO `sc` VALUES ('10', '4', '1', '48');
   INSERT INTO `sc` VALUES ('11', '5', '2', '60');
   INSERT INTO `sc` VALUES ('12', '5', '3', '45');
   INSERT INTO `sc` VALUES ('13', '4', '2', '59');
   
   
   -- ----------------------------
   -- Table structure for student
   -- ----------------------------
   DROP TABLE IF EXISTS `student`;
   CREATE TABLE `student` (
     `Sid` int(11) NOT NULL AUTO_INCREMENT,
     `Sname` varchar(20) DEFAULT NULL,
     `Sage` int(11) DEFAULT NULL,
     `Ssex` varchar(2) DEFAULT NULL,
     PRIMARY KEY (`Sid`)
   ) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8mb4;
   
   -- ----------------------------
   -- Records of student
   -- ----------------------------
   INSERT INTO `student` VALUES ('1', 'student1', '1', '1');
   INSERT INTO `student` VALUES ('2', 'student2', '2', '1');
   INSERT INTO `student` VALUES ('3', 'student3', '3', '1');
   INSERT INTO `student` VALUES ('4', 'student4', '4', '2');
   INSERT INTO `student` VALUES ('5', 'student5', '5', '2');
   INSERT INTO `student` VALUES ('6', 'student6', '6', '2');
   
   
   
   -- ----------------------------
   -- Table structure for teacher
   -- ----------------------------
   DROP TABLE IF EXISTS `teacher`;
   CREATE TABLE `teacher` (
     `Tid` int(11) NOT NULL AUTO_INCREMENT,
     `Tname` varchar(20) DEFAULT NULL,
     PRIMARY KEY (`Tid`)
   ) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4;
   
   -- ----------------------------
   -- Records of teacher
   -- ----------------------------
   INSERT INTO `teacher` VALUES ('1', 'mike');
   INSERT INTO `teacher` VALUES ('2', 'male');
   INSERT INTO `teacher` VALUES ('3', 'jom');

   查詢:

   #1、查詢“001”課程比“002”課程成績高的所有學生的學號；  
   SELECT a.sid FROM (SELECT sid,score FROM sc WHERE sc.Cid = '001') a,
   (SELECT sid,score FROM sc WHERE sc.Cid = '002') b WHERE
   a.sid = b.sid AND a.score > b.score;
   #2、查詢平均成績大於60分的同學的學號和平均成績；
   SELECT sid,avg(score) vv FROM sc GROUP BY Sid HAVING vv > 60;
   #3、查詢所有同學的學號、姓名、選課數、總成績；  
   SELECT s.sid,s.sname,COUNT(sc.Cid),SUM(sc.score) FROM student s LEFT JOIN sc on s.Sid = sc.Sid GROUP BY s.Sid;
   #4、查詢m開頭的老師的個數
   SELECT COUNT(*) FROM teacher WHERE tname like "m%";
   #5、查詢沒學過“mike”老師課的同學的學號、姓名；  
   SELECT * FROM student WHERE sid not  in(
   SELECT sid FROM sc WHERE cid in(
   SELECT cid FROM course WHERE tid in(SELECT tid FROM teacher WHERE tname = 'mike')
   )
   );
   --
   SELECT * FROM student WHERE sid not in(
   SELECT sc.sid FROM sc,course c,teacher t WHERE t.tname = 'mike' and t.tid = c.tid AND c.cid = sc.Cid
   );
   #6、查詢學過“001”並且也學過編號“002”課程的同學的學號、姓名
   SELECT sid,Sname FROM student WHERE sid in(
   SELECT a.sid FROM 
   (SELECT sc.sid FROM sc,course c WHERE c.Cname = '001' and c.cid =sc.cid) a, 
   (SELECT sc.sid FROM sc,course c WHERE c.Cname = '002' and c.cid =sc.cid) b
   where a.sid = b.sid
   );
   --
   SELECT s.sid,s.sname FROM student s,sc,course c where s.sid = sc.sid and c.cname='001' 
   and c.cid = sc.cid and EXISTS 
   (SELECT * FROM course c2,sc as sc2 WHERE c2.cname = '002' and c2.cid = sc2.cid and sc2.sid = s.sid);
   #7、查詢學過“jom”老師所教的所有課的同學的學號、姓名；  
   SELECT sid,sname FROM student WHERE sid in(
   SELECT Sid FROM sc WHERE cid in(
   SELECT cid FROM course WHERE tid in(SELECT tid FROM teacher WHERE Tname = 'jom')
   )
   );
   --
   SELECT sid,sname FROM student WHERE sid in(
   SELECT sc.Sid FROM sc,course c,teacher t WHERE t.tname = 'jom' and t.tid = c.tid AND sc.cid = c.cid;
   )
   #8、查詢所有課程成績小於60分的同學的學號、姓名
   SELECT sid,sname FROM student WHERE sid not in(
   SELECT sid FROM sc where score > 60;
   )
   #9、查詢沒有學全所有課的同學的學號、姓名；  
   SELECT s.sid,s.sname FROM student s LEFT JOIN sc on s.sid = sc.Sid GROUP BY s.sid 
   HAVING COUNT(sc.cid) < (SELECT COUNT(*) FROM course);
   #10、查詢至少有一門課與學號爲“1”的同學所學相同的同學的學號和姓名；
   SELECT DISTINCT s.sid,s.Sname FROM student s,sc WHERE s.Sid = sc.Sid
   AND sc.cid  in(SELECT cid FROM sc WHERE Sid = 5);
   #11、查出所有課程成績最高和最低的學生id及其分數
   SELECT 'hight',sc.* FROM sc,(SELECT MAX(score) as score,cid FROM sc GROUP BY Cid) b
   WHERE sc.score = b.score AND sc.Cid = b.cid
   UNION
   SELECT 'low',sc.* FROM sc,(SELECT min(score) as score,cid FROM sc GROUP BY Cid) b
   WHERE sc.score = b.score AND sc.Cid = b.cid;
   #12、查詢各科成績最高和最低的分：以如下形式顯示：課程ID，最高分，最低分 
   SELECT cid,max(score),min(score) FROM sc GROUP BY sc.Cid;
   --
   SELECT l.cid,l.score max,r.score min FROM sc l,sc r WHERE l.Cid = r.Cid
   AND l.score = (SELECT MAX(il.score) FROM sc il,student s WHERE il.cid = l.Cid and s.sid = il.sid GROUP BY il.cid)
   and r.score = (SELECT MIN(ir.score) FROM sc ir WHERE ir.cid = r.Cid GROUP BY ir.cid)
   ORDER BY l.cid ASC;
   #13、查詢學生平均成績及其名次
   SELECT sid,AVG(score) avg_sc FROM sc GROUP BY sid ORDER BY avg_sc DESC;
   --
   SELECT 1+(SELECT COUNT(DISTINCT avg_sc) FROM (SELECT sid,AVG(score) avg_sc FROM sc GROUP BY sid)T1
   WHERE avg_sc > T2.avg_sc) '名次',sid, avg_sc FROM (SELECT sid,AVG(score) avg_sc FROM sc GROUP BY sid)T2
   ORDER BY avg_sc desc;
   --
   SELECT @rownum:=@rownum+1 as ind,obj.sid,obj.avg_sc FROM
   (SELECT sid,AVG(score) avg_sc FROM sc GROUP BY sid ORDER BY avg_sc DESC) as obj,
   (SELECT @rownum:=0) r;
   #14、查詢各科成績前三名的記錄:(不考慮成績並列情況)
   SELECT * FROM sc x WHERE 3 >(
   SELECT COUNT(*) FROM sc y WHERE x.score < y.score and x.cid=y.cid)
   ORDER BY cid,score DESC