本文适合哪些人群

• 致力于将SQL作为自己的技术特长的人
• 想在日常工作中和面试中突出自己SQL能力的人

SQL建表语句

CREATE TABLE STUDENT ( SNO VARCHAR(3) NOT NULL, SNAME VARCHAR(4) NOT NULL, SSEX VARCHAR(2) NOT NULL, SBIRTHDAY DATETIME, CLASS VARCHAR(5) );

CREATE TABLE COURSE ( CNO VARCHAR(5) NOT NULL, CNAME VARCHAR(10) NOT NULL, TNO VARCHAR(10) NOT NULL );

CREATE TABLE SCORE ( SNO VARCHAR(3) NOT NULL, CNO VARCHAR(5) NOT NULL, DEGREE NUMERIC(10, 1) NOT NULL );

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 );

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 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', 100);

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 (101, '6-166', 85);
INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (107, '6-106', 79);
INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (108, '3-105', 78);
INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (108, '6-166', 81);

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');

SQL实战

-- 1、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 );
-- 2、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),CNO FROM score WHERE CNO LIKE '3%' GROUP BY CNO HAVING COUNT(*) >5;

-- 3、查询所有学生的Sname、Cname和Degree列。
SELECT A.SNAME, B.CNAME, C.DEGREE FROM STUDENT A JOIN (COURSE B, SCORE C) ON A.SNO = C.SNO AND B.CNO = C.CNO;

SELECT a.SNAME,b.CNAME,c.DEGREE FROM student a LEFT JOIN course b LEFT JOIN score c WHERE a.SNO=c.SNO AND b.CNO=c.CNO;

 -- 4、查询“95033”班所选课程的平均分。
SELECT AVG( DEGREE) FROM score WHERE sno in（select sno from student WHERE class='95033'） -- 5、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 * FROM score WHERE CNO="3-105" AND DEGREE > ALL (SELECT DEGREE FROM score WHERE SNO='109') -- 6、查询教师所有的单位即不重复的Depart列。 select distinct DEPART from TEACHER;

-- 7、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 ) GROUP BY SNO HAVING COUNT(*) >1;

-- 8、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' );

-- 9、查询“张旭“教师任课的学生成绩。
SELECT * FROM score WHERE CNO= (SELECT CNO FROM course,teacher WHERE course.TNO=teacher.TNO AND teacher.TNAME='张旭' );

-- 10、查询存在有85分以上成绩的课程Cno
SELECT CNO FROM score GROUP BY CNO HAVING MAX(DEGREE) >85;

-- 11、查询出“计算机系“教师所教课程的成绩表。
SELECT * FROM score WHERE CNO IN(SELECT CNO FROM teacher,course WHERE DEPART='计算机系' and course.TNO=teacher.TNO);
)

-- 12、查询所有教师和同学的name、sex和birthday.
select TNAME name, TSEX sex, TBIRTHDAY birthday from TEACHER union select sname name, SSEX sex, SBIRTHDAY birthday from STUDENT;

-- 13、查询所有“女”教师和“女”同学的name、sex和birthday.
select TNAME name, TSEX sex, TBIRTHDAY birthday from TEACHER where TSEX = '女' union select sname name, SSEX sex, SBIRTHDAY birthday from STUDENT where SSEX = '女';

-- 14、查询所有任课教师的Tname和Depart.
SELECT TNAME,Depart FROM teacher a WHERE EXISTS ( SELECT * FROM teacher,course b WHERE a.TNO=b.TNO ) -- 15、查询至少有2名男生的班号。 SELECT CLASS FROM student WHERE SSEX='男' GROUP BY CLASS HAVING COUNT(SSEX)>1;

-- 16、查询Student表中每个学生的姓名和年龄。
select SNAME, (year(now()) - year(SBIRTHDAY)) age from STUDENT;

-- 17、查询Student表中最大和最小的Sbirthday日期值。
select MAX(SBIRTHDAY) FROM student UNION SELECT MIN(SBIRTHDAY) FROM student;

-- 18、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,year(NOW())-year(SBIRTHDAY) DESC;

-- 19、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);

-- 20、查询和“李军”同性别并同班的同学Sname.
SELECT Sname FROM student WHERE (SSEX,CLASS) =(SELECT SSEX,CLASS FROM student WHERE SNAME='李军');

-- 21、查询所有选修“计算机导论”课程的“男”同学的成绩表
select * from score,student where score.sno=student.sno and SSEX='男' and CNO=(SELECT CNO from course where CNAME='计算机导论');

-- 22、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' ) -- 23、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 Cno,SNO,DEGREE FROM score WHERE CNO='3-105' AND DEGREE >ANY ( SELECT DEGREE FROM score WHERE CNO='3-245' ) ORDER BY DEGREE DESC;

-- 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 WHERE TNO=( SELECT TNO FROM course WHERE CNO=( SELECT CNO FROM score GROUP BY CNO HAVING COUNT(SNO) >5) ) ) -- 25、查询成绩比该课程平均成绩低的同学的成绩表(自关联)。 SELECT A.* FROM SCORE A WHERE DEGREE < (SELECT AVG(DEGREE) FROM SCORE B WHERE A.CNO = B.CNO);

CREATE TABLE ta (
id int(11) NOT NULL AUTO_INCREMENT,
pname varchar(20) DEFAULT NULL,
sale int(11) DEFAULT NULL,
datet datetime DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (id)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8mb4;

INSERT INTO ta VALUES (‘1’, ‘小强’, ‘1111’, ‘2018-08-06 18:05:18’);
INSERT INTO ta VALUES (‘2’, ‘小明’, ‘23132’, ‘2018-08-06 18:05:35’);
INSERT INTO ta VALUES (‘3’, ‘小红’, ‘4444444’, ‘2018-08-06 18:05:47’);
INSERT INTO ta VALUES (‘4’, ‘小红’, ‘4545’, ‘2018-08-07 18:06:04’);
INSERT INTO ta VALUES (‘5’, ‘小强’, ‘888888’, ‘2018-08-07 18:06:19’);
INSERT INTO ta VALUES (‘6’, ‘小明’, ‘435435’, ‘2018-08-07 18:06:35’);

-- 查询当天的商品信息，商品顺序为前一天销量前三的商品
SELECT t.id,t.pname,t.sale as 前一天,t2.sale 后一天 from(SELECT * from ta where DATE_FORMAT(datet,'%Y-%m-%d')='2018-08-06')t INNER JOIN (SELECT * from ta where DATE_FORMAT(datet,'%Y-%m-%d')='2018-08-07' ) t2 on t.pname=t2.pname ORDER BY t.sale desc