SQL语句50题基础练习

CREATE DATABASE 50q;
USE 50q;
 
CREATE TABLE STUDENT
(
 SNO       VARCHAR(3) NOT NULL, 
 SNAME     VARCHAR(4) NOT NULL,
 SSEX      VARCHAR(2) NOT NULL, 
 SBIRTHDAY DATETIME,
 CLASS     VARCHAR(5)
 );
 -- VARCHAR(M) 每个值占用的字节长度=该值字节数+1，M只是其最大值--
 -- MySQL retrieves and displays DATETIME values in 'YYYY-MM-DD HH:MM:SS' format--
 
CREATE TABLE COURSE
(
 CNO   VARCHAR(5)  NOT NULL, 
 CNAME VARCHAR(10) NOT NULL, 
 TNO   VARCHAR(3) NOT NULL
 );
 
 CREATE TABLE SCORE 
(
 SNO    VARCHAR(3)     NOT NULL, 
 CNO    VARCHAR(5)     NOT NULL, 
 DEGREE NUMERIC(10, 1) NOT NULL
 ) ;
 -- NUMERIC(5,2)的赋值范围是[-999.99,999.99]--
 -- NUMERIC(M)等价于NUMERIC(M,0), NUMERIC等价于NUMERIC(10)--
 
 CREATE TABLE TEACHER 
(
 TNO       VARCHAR(3)  NOT NULL, 
 TNAME     VARCHAR(4)  NOT NULL, 
 TSEX      VARCHAR(2)  NOT NULL, 
 TBIRTHDAY DATETIME    NOT NULL, 
 PROF      VARCHAR(6), 
 DEPART    VARCHAR(10) NOT NULL
 );
 
 ALTER TABLE STUDENT ADD PRIMARY KEY (SNO);
 ALTER TABLE SCORE   ADD PRIMARY KEY (SNO,CNO);
 ALTER TABLE COURSE  ADD PRIMARY KEY (CNO);
 ALTER TABLE TEACHER ADD PRIMARY KEY (TNO);
 
-- 先添加外键，再添加值--
-- 外键在两张table中的数据类型须一致--
 ALTER TABLE SCORE   ADD CONSTRAINT FK_SCORE_STUDENT  FOREIGN KEY (SNO) REFERENCES STUDENT(SNO);
 ALTER TABLE SCORE   ADD CONSTRAINT FK_SCORE_COURSE   FOREIGN KEY (CNO) REFERENCES COURSE(CNO);
 ALTER TABLE COURSE  ADD CONSTRAINT FK_COURSE_TEACHER FOREIGN KEY (TNO) REFERENCES TEACHER(TNO);
 
 -- 先对REFERENCES中所指的表添加值--
 INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) 
 VALUES (108 ,'曾华' ,'男' ,'1977-09-01',95033);
 INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) 
 VALUES (105 ,'匡明' ,'男' ,'1975-10-02',95031);
 INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) 
 VALUES (107 ,'王丽' ,'女' ,'1976-01-23',95033);
 INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) 
 VALUES (101 ,'李军' ,'男' ,'1976-02-20',95033);
 INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) 
 VALUES (109 ,'王芳' ,'女' ,'1975-02-10',95031);
 INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) 
 VALUES (103 ,'陆君' ,'男' ,'1974-06-03',95031);
 
 INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) 
 VALUES (804,'李诚','男','1958-12-02','副教授','计算机系');
 INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) 
 VALUES (856,'张旭','男','1969-03-12','讲师','电子工程系');
 INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART)
 VALUES (825,'王萍','女','1972-05-05','助教','计算机系');
 INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) 
 VALUES (831,'刘冰','女','1977-08-14','助教','电子工程系');
 
 INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('3-105' ,'计算机导论',825);
 INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('3-245' ,'操作系统' ,804);
 INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('6-166' ,'数据电路' ,856);
 INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('9-888' ,'高等数学' ,831);
 
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (103,'3-245',86);
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (105,'3-245',75);
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (109,'3-245',68);
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (103,'3-105',92);
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (105,'3-105',88);
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (109,'3-105',76);
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (101,'3-105',64);
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (107,'3-105',91);
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (108,'3-105',78);
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (101,'6-166',85);
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (107,'6-166',79);
 INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (108,'6-166',81);

-- 1、 查询Student表中的所有记录的Sname、Ssex和Class列。--
SELECT SNAME,SSEX,CLASS FROM STUDENT;
 
-- 2、 查询教师所有的单位即不重复的Depart列。--
SELECT DISTINCT DEPART FROM TEACHER;
 
-- 3、 查询Student表的所有记录。--
SELECT * FROM STUDENT;
 
-- 4、 查询Score表中成绩在60到80之间的所有记录。--
SELECT * FROM SCORE
WHERE DEGREE>=60 AND DEGREE<=80;
 
SELECT * FROM SCORE
WHERE DEGREE BETWEEN 60 AND 80; /*BETWEEN AND: 取值包括两边界*/
 
-- 5、 查询Score表中成绩为85，86或88的记录。--
SELECT * FROM SCORE
WHERE DEGREE=85 OR DEGREE=86 OR DEGREE=88;
 
SELECT * FROM SCORE
WHERE DEGREE IN (85,86,88);
 
-- 6、 查询Student表中“95031”班或性别为“女”的同学记录。--
SELECT * FROM STUDENT
WHERE CLASS=95031 OR SSEX='女';
 
-- 7、 以Class降序查询Student表的所有记录。--
SELECT * FROM STUDENT
ORDER BY CLASS DESC;
 
-- 8、 以Cno升序、Degree降序查询Score表的所有记录。--
SELECT * FROM SCORE
ORDER BY CNO, DEGREE DESC;
 
-- 9、 查询“95031”班的学生人数。--
SELECT COUNT(*) FROM STUDENT
WHERE CLASS=95031;
 
-- 10、查询Score表中的最高分的学生学号和课程号。--
SELECT SNO,CNO FROM SCORE
WHERE DEGREE=(SELECT MAX(DEGREE) FROM SCORE);
 
SELECT SNO,CNO FROM SCORE
ORDER BY DEGREE DESC
LIMIT 1;
 
-- 11、查询‘3-105’号课程的平均分。--
SELECT AVG(DEGREE) FROM SCORE
WHERE CNO='3-105';
 
-- 12、查询Score表中至少有5名学生选修的并以3开头的课程的平均分数。--
SELECT AVG(DEGREE) FROM SCORE
WHERE CNO LIKE'3%' 
GROUP BY CNO
HAVING COUNT(*)>=5;
 
-- 13、查询最低分大于70，最高分小于90的Sno列。--
SELECT SNO FROM SCORE
GROUP BY SNO
HAVING MAX(DEGREE)<90 AND MIN(DEGREE)>70;
 
-- 14、查询所有学生的Sname、Cno和Degree列。--
SELECT SNAME,CNO,DEGREE 
FROM STUDENT,SCORE
WHERE STUDENT.SNO=SCORE.SNO;
 
SELECT SNAME,CNO,DEGREE
FROM STUDENT INNER JOIN SCORE
ON STUDENT.SNO=SCORE.SNO;
 
-- 15、查询所有学生的Sno、Cname和Degree列。--
SELECT SNO,CNAME,DEGREE
FROM SCORE,COURSE
WHERE SCORE.CNO=COURSE.CNO;
 
SELECT SNO,CNAME,DEGREE
FROM SCORE INNER JOIN COURSE
ON SCORE.CNO=COURSE.CNO;
 
-- 16、查询所有学生的Sname、Cname和Degree列。--
SELECT SNAME,CNAME,DEGREE
FROM STUDENT,COURSE,SCORE
WHERE STUDENT.SNO=SCORE.SNO
AND COURSE.CNO=SCORE.CNO;
 
-- 17、查询“95033”班所选课程的平均分。--
SELECT AVG(DEGREE) 
FROM SCORE,STUDENT
WHERE SCORE.SNO=STUDENT.SNO
AND CLASS=95033;
 
SELECT AVG(DEGREE) 
FROM SCORE INNER JOIN STUDENT
ON SCORE.SNO=STUDENT.SNO
WHERE CLASS=95033;
 
-- 18、假设使用如下命令建立了一个grade表：
-- CREATE TABLE GRADE
-- (
-- LOW  NUMERIC(3,0),
-- UPP  NUMERIC(3),
-- RANK CHAR(1)
-- );
-- INSERT INTO GRADE
-- VALUES(90,100,'A');
-- INSERT INTO GRADE
-- VALUES(80,89,'B');
-- INSERT INTO GRADE
-- VALUES(70,79,'C');
-- INSERT INTO GRADE
-- VALUES(60,69,'D');
-- INSERT INTO GRADE
-- VALUES(0,59,'E');
-- COMMIT;
-- 现查询所有同学的Sno、Cno和rank列。--
SELECT SNO,CNO,DEGREE
FROM SCORE INNER JOIN GRADE
WHERE DEGREE BETWEEN LOW AND UPP;
 
-- 19、查询选修“3-105”课程的成绩高于“109”号同学成绩的所有同学的记录。--
SELECT A.* 
FROM SCORE AS A JOIN SCORE AS B 
WHERE A.CNO='3-105' 
AND A.DEGREE>B.DEGREE 
AND B.SNO='109' 
AND B.CNO='3-105';
 
SELECT * FROM SCORE
WHERE CNO='3-105' AND DEGREE>(SELECT DEGREE FROM SCORE
							   WHERE CNO='3-105' AND SNO=109);
                               
-- 20、查询score中选学一门以上课程的同学中分数为非最高分成绩的记录。--
SELECT * FROM SCORE
WHERE DEGREE<(SELECT MAX(DEGREE) FROM SCORE)
AND SNO IN(SELECT SNO FROM SCORE
           GROUP BY SNO
		   HAVING COUNT(*)>1);
 
-- 21、查询成绩高于学号为“109”、课程号为“3-105”的成绩的所有记录。--
SELECT A.* FROM SCORE AS A INNER JOIN SCORE AS B
WHERE B.SNO=109 AND B.CNO='3-105' AND A.CNO='3-105'AND A.DEGREE>B.DEGREE;
 
-- 22、查询和学号为108的同学同年出生的所有学生的Sno、Sname和Sbirthday列。--
SELECT SNO,SNAME,SBIRTHDAY 
FROM STUDENT
WHERE YEAR(SBIRTHDAY)=(SELECT YEAR(SBIRTHDAY) FROM STUDENT
					   WHERE SNO=108);
 
-- 23、查询“张旭“教师任课的学生成绩。--
SELECT DEGREE 
FROM SCORE,TEACHER,COURSE
WHERE SCORE.CNO=COURSE.CNO
AND COURSE.TNO=TEACHER.TNO
AND TEACHER.TNAME='张旭';
 
-- 24、查询选修某课程的同学人数多于5人的教师姓名。
SELECT TNAME
FROM TEACHER,COURSE,SCORE
WHERE TEACHER.TNO=COURSE.TNO
AND COURSE.CNO=SCORE.CNO
GROUP BY SCORE.CNO
HAVING COUNT(*)>5;
 
-- 25、查询95033班和95031班全体学生的记录。--
SELECT * FROM STUDENT
WHERE CLASS IN (95033,95031);
 
-- 26、查询存在有85分以上成绩的课程Cno.--
SELECT DISTINCT CNO FROM SCORE
WHERE DEGREE>85;
 
-- 27、查询出“计算机系“教师所教课程的成绩表。--
SELECT DEGREE FROM SCORE,TEACHER,COURSE
WHERE SCORE.CNO=COURSE.CNO
AND COURSE.TNO=TEACHER.TNO
AND TEACHER.DEPART='计算机系';
 
-- 28、查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。--
SELECT TNAME,PROF FROM TEACHER
WHERE DEPART='计算机系' 
AND PROF NOT IN (SELECT PROF FROM TEACHER 
                 WHERE DEPART='电子工程系'); 
 
-- 29、查询选修编号为“3-105“课程且成绩至少高于选修编号为“3-245”的同学的Cno、Sno和Degree,并按Degree从高到低次序排序。--
SELECT * FROM SCORE 
WHERE DEGREE>ANY(SELECT DEGREE FROM SCORE WHERE CNO='3-245')
AND CNO='3-105'
ORDER BY DEGREE DESC;
 
-- 30、查询选修编号为“3-105”且成绩高于选修编号为“3-245”课程的同学的Cno、Sno和Degree.--
SELECT * FROM SCORE 
WHERE DEGREE>ALL(SELECT DEGREE FROM SCORE WHERE CNO='3-245')
AND CNO='3-105';
 
-- 31、查询所有教师和同学的name、sex和birthday.--
SELECT SNAME AS NAME,SSEX AS SEX,SBIRTHDAY AS BIRTHDAY
FROM STUDENT
UNION
SELECT TNAME AS NAME,TSEX AS SEX,TBIRTHDAY AS BIRTHDAY
FROM TEACHER;
 
-- 32、查询所有“女”教师和“女”同学的name、sex和birthday.--
SELECT SNAME AS NAME,SSEX AS SEX,SBIRTHDAY AS BIRTHDAY
FROM STUDENT
WHERE SSEX='女'
UNION
SELECT TNAME AS NAME,TSEX AS SEX,TBIRTHDAY AS BIRTHDAY
FROM TEACHER
WHERE TSEX='女';
 
-- 33、查询成绩比该课程平均成绩低的同学的成绩表。--
SELECT A.*
FROM SCORE AS A LEFT OUTER JOIN SCORE AS B
ON A.CNO=B.CNO
GROUP BY A.SNO,B.CNO
HAVING A.DEGREE<AVG(B.DEGREE);
 
SELECT A.* FROM SCORE AS A 
WHERE DEGREE<(SELECT AVG(DEGREE) FROM SCORE AS B 
              WHERE A.CNO=B.CNO);
 
-- 34、查询所有任课教师的Tname和Depart.--
SELECT TNAME,DEPART
FROM TEACHER,COURSE
WHERE TEACHER.TNO=COURSE.TNO;
 
SELECT A.TNAME,A.DEPART 
FROM TEACHER A INNER JOIN COURSE B 
ON A.TNO=B.TNO;
 
SELECT TNAME,DEPART FROM TEACHER AS A
WHERE EXISTS(SELECT * FROM COURSE AS B
			 WHERE A.TNO=B.TNO);
 
SELECT TNAME,DEPART FROM TEACHER
WHERE TNO IN (SELECT TNO FROM COURSE);
 
-- 35  查询所有未讲课的教师的Tname和Depart.--
SELECT TNAME,DEPART FROM TEACHER
WHERE TNO NOT IN (SELECT TNO FROM COURSE);  /*NOT IN效率最差*/
 
SELECT TNAME,DEPART 
FROM TEACHER AS A LEFT JOIN COURSE AS B
USING (TNO)
WHERE B.TNO IS NULL;
 
SELECT TNAME,DEPART FROM TEACHER AS A
WHERE NOT EXISTS (SELECT * FROM COURSE AS B
			      WHERE A.TNO=B.TNO);
 
-- 36、查询至少有2名男生的班号。--
SELECT CLASS FROM STUDENT
GROUP BY CLASS,SSEX
HAVING COUNT(*)>=2;
 
SELECT CLASS FROM STUDENT 
WHERE SSEX='男' 
GROUP BY CLASS 
HAVING COUNT(SSEX)>1;
 
-- 37、查询Student表中不姓“王”的同学记录。--
SELECT * FROM STUDENT
WHERE SNAME NOT LIKE '王%';
 
-- 38、查询Student表中每个学生的姓名和年龄。--
SELECT SNAME,YEAR(NOW())-YEAR(SBIRTHDAY) AS AGE
FROM STUDENT;
 
-- 39、查询Student表中最大和最小的Sbirthday日期值。--
SELECT MAX(SBIRTHDAY),MIN(SBIRTHDAY)
FROM STUDENT;
 
-- 40、以班号和年龄从大到小的顺序查询Student表中的全部记录。--
SELECT * FROM STUDENT
ORDER BY CLASS DESC,SBIRTHDAY;
 
-- 41、查询“男”教师及其所上的课程。--
SELECT TEACHER.TNO,TNAME,CNO
FROM TEACHER INNER JOIN COURSE
ON TEACHER.TNO=COURSE.TNO
WHERE TSEX='男';
 
-- 42、查询最高分同学的Sno、Cno和Degree列。--
SELECT SNO,CNO,DEGREE
FROM SCORE
WHERE DEGREE=(SELECT MAX(DEGREE) FROM SCORE);
 
-- 43、查询和“李军”同性别的所有同学的Sname.--
SELECT SNAME FROM STUDENT
WHERE SSEX=(SELECT SSEX FROM STUDENT
            WHERE SNAME='李军');
            
SELECT A.SNAME
FROM STUDENT AS A, STUDENT AS B
WHERE A.SSEX=B.SSEX
AND B.SNAME='李军';
 
-- 44、查询和“李军”同性别并同班的同学Sname.--
SELECT A.SNAME
FROM STUDENT AS A, STUDENT AS B
WHERE A.SSEX=B.SSEX
AND A.CLASS=B.CLASS
AND B.SNAME='李军';
 
-- 45、查询所有选修“计算机导论”课程的“男”同学的成绩表--
SELECT STUDENT.SNO,DEGREE
FROM SCORE,STUDENT,COURSE
WHERE SCORE.CNO=COURSE.CNO
AND STUDENT.SNO=SCORE.SNO
AND COURSE.CNAME='计算机导论'
AND STUDENT.SSEX='男';

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