mysql 综合查询_mysql 综合查询练习（关系查询、子查询）
建表语句见文末empsalarygrade
1、找到名字为两位的员工信息
-- 方法一
select * from emp
where length(ename) = 6; #一个汉字的长度为3
-- 方法二
select * from emp
where ename like '__'; -- 两根下划线
2、查询工资多于宋江的员工信息 (子查询)
select * from emp
where salary > (select salary from emp where ename = '宋江');
3、查询销售部门的员工姓名
-- 法一：join
select dname , ename from
emp left join dept on emp.dept_id = dept.id
where dname = '销售部';
-- 法二：关系查询
select ename , dname
from emp , dept
where emp.dept_id = dept.id and dname = '销售部'; -- 关系连接 ,结果和内连接一样
-- 法三：子查询
select ename from emp
where dept_id = (select id from dept where dname = '销售部'); -- 子查询没法将部门名称放上去
4、返回工资级别处于第4的员工姓名及工资(子查询作为虚拟表) ***
select ename , salary from emp ,(select losalary , hisalary from salarygrade where grade = 4) as a
where salary between losalary and hisalary;
5、-- 查询所有员工对应的工资等级 ***
6、查询选修编号为“3-105“课程且成绩至少高于课程选修编号为“3-245”的记录,并按Degree从高到低降序排序。
select * from score
where cno = '3-105' and degree >any (select degree from score where cno = '3-245')
order by degree desc;
7、查询选修编号为“3-105”且成绩高于选修编号为“3-245”课程的记录
select * from score
where cno = '3-105' and degree >all (select degree from score where cno = '3-245')
order by degree desc;
8、查询至少有2名男生的班号 ****
select * from student;
select class , ssex , count(sno) from student
where ssex = '男'
group by class having count(sno) >= 2;
9、查询所有“女”教师和“女”同学的name、sex和birthday
(select tname , tsex , tbirthday from teacher where tsex = '女')
union
(select sname , ssex , sbirthday from student where ssex = '女');
-----------------------------------------建表语句---------------------------------------------
1、emp表
-- 创建员工表emp
create table emp (
id int primary key,
ename varchar(50),
job_id int,
mgr int,
joindate date,
salary decimaL(7 , 2 ),
bonus decimal(7 , 2 ),
dept_id int
);
#添加员工
insert into emp(id,ename,job_id,mgr,joindate,salary,bonus,dept_id)
values (1001,'孙悟空',4,1004,'2000-12-17','8000.00',NULL,20),
(1002,'卢俊义',3,1006,'2001-02-20','16000.00','3000.00',30),
(1003,'林冲',3,1006,'2001-02-22','12500.00','5000.00',30),
(1004,'唐僧',2,1009,'2001-04-02','29750.00',NULL,20),
(1005,'李逵',4,1006,'2001-09-28','12500.00','14000.00',30),
(1006,'宋江',2,1009,'2001-05-01','28500.00',NULL,30),
(1007,'刘备',2,1009,'2001-09-01','24500.00',NULL,10),
(1008,'猪八戒',4,1004,'2007-04-19','30000.00',NULL,20),
(1009,'罗贯中',1,NULL,'2001-11-17','50000.00',NULL,10),
(1010,'吴用',3,1006,'2001-09-08','15000.00','0.00',30),
(1011,'沙僧',4,1004,'2007-05-23','11000.00',NULL,20),
(1012,'白骨精',4,1006,'2001-12-03','9500.00',NULL,30),
(1013,'小白龙',4,1004,'2001-12-03','30000.00',NULL,20),
(1014,'关羽',4,1007,'2002-01-23','13000.00',NULL,10);
select * from emp;
salarygrade表
-- 创建薪资等级表
create table salarygrade (
grade int primary key,
losalary int,
hisalary int
);
#添加5个工资等级
insert into salarygrade(grade,losalary,hisalary)
values (1,7000,12000),
(2,12010,14000),
(3,14010,20000),
(4,20010,30000),
(5,30010,99990);
select * from salarygrade;
2、student 表 、score表、course表、teacher表
/*-------------------建表-------------------------*/
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(3) 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
);
/*---------------添加主键--------------*/
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);
/*---------------输入记录-------------------*/
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS)
VALUES (108 ,'曾华' ,'男' ,'1977-09-01',95033),
(105 ,'匡明' ,'男' ,'1975-10-02',95031),
(107 ,'王丽' ,'女' ,'1976-01-23',95033),
(101 ,'李军' ,'男' ,'1976-02-20',95033),
(109 ,'王芳' ,'女' ,'1975-02-10',95031),
(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'),
(856,'张旭','男','1969-03-12','讲师','电子工程系'),
(825,'王萍','女','1972-05-05','助教','计算机系'),
(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),
('3-245' ,'操作系统' ,804),
('6-166' ,'数据电路' ,856),
('9-888' ,'高等数学' ,831);
INSERT INTO SCORE(SNO,CNO,DEGREE)
VALUES (103,'3-245',86),(105,'3-245',75),
(109,'3-245',68),(103,'3-105',92),
(105,'3-105',88),(109,'3-105',76),
(101,'3-105',64),(107,'3-105',91),
(108,'3-105',78),(101,'6-166',85),
(107,'6-166',79),(108,'6-166',81);
select * from student;
select * from course;
select * from teacher;
select * from score;