练习题
create database mydb1;
create database mydb2 character set utf8;
create database mydb3 character set utf8 collate utf8_general_ci;
alter database mydb2 default character set gbk;
drop database mydb3;
show databases;
show create database mydb1;
use mydb1;
create table employee (
id int primary key auto_increment,
name varchar(32) not null,
gender varchar(32),
birthday date,
entry_date date,
job varchar(32),
salary double,
resume text
);
create table employee2 (
id int primary key auto_increment,
name varchar(32) not null,
gender varchar(32),
birthday date,
entry_date date,
job varchar(32),
salary double,
resume text
);
drop table employee2
alter table employee add image varchar(20);
alter table employee modify job varchar(60);
alter table employee drop gender;
rename table employee to user;
alter table user character set utf8;
alter table user change name username varchar(32) not null;
show tables;
rename table user to employee;
show create table employee;
desc employee;
insert into employee(username) values('zs'),('lisi'),('wangwu');
update employee set salary = 5000;
update employee set salary = 3000 where username='zs';
update employee set salary = 3000,job = 'ccc' where username='lisi';
update employee set salary = salary + 1000 where username='wangwu';
delete from employee where username='zs';
delete from employee;
alter database mydb1 default character set utf8;
create table exam(
id int primary key auto_increment,
name varchar(20) not null,
chinese double,
math double,
english double
);
insert into exam values(null,'关羽',85,76,70);
insert into exam values(null,'张飞',70,75,70);
insert into exam values(null,'赵云',90,65,95);
insert into exam values(null,'刘备',97,50,50);
insert into exam values(null,'曹操',90,89,80);
insert into exam values(null,'司马懿',90,67,65);
select * from exam;
select name '姓名',english '英语成绩' from exam;
select distinct * from exam group by name;
select name,chinese+10 from exam;
select name,(chinese + math+ english) '总分' from exam;
select name '姓名',chinese '语文',math '数学',english '英语' from exam;
select * from exam where name='刘备';
select name from exam where english > 90;
select name from exam where (chinese + math+ english)>200;
select name from exam where english between 80 and 90;
select name from exam where math in(89,75,91);
select name from exam where name like('刘%');
select name from exam where name like('刘_');
select name from exam where math>80 and chinese>80;
select name from exam where math>80 or chinese>80;
select * from exam group by math;
select * from exam group by (chinese + math+ english) DESC;
select * from exam where name like('刘%') group by (chinese + math+ english);
select count(name) from exam;
select count(name) from exam where math>=90;
select count(*) from exam where (math+chinese+english)>250;
select sum(math) from exam;
select sum(math) '数学总成绩',sum(chinese) '语文总成绩',sum(english) '英语总成绩' from exam;
select sum(math)+sum(chinese)+sum(english) 's语数英成绩总和' from exam;
select avg(chinese) from exam;
select avg(math) from exam;
select avg(math+chinese+english) from exam;
select max(math+chinese+english) '最高分',min(math+chinese+english) '最低分' from exam;
create table orders(
id int,
product varchar(20),
price float
);
insert into orders(id,product,price) values(1,'电视',900);
insert into orders(id,product,price) values(2,'洗衣机',100);
insert into orders(id,product,price) values(3,'洗衣粉',90);
insert into orders(id,product,price) values(4,'桔子',9);
insert into orders(id,product,price) values(5,'洗衣粉',90);
select product,sum(price) from orders where price > 100 group by product;
CREATE TABLE emp(
empno INT,
ename VARCHAR(50),
job VARCHAR(50),
mgr INT,
hiredate DATE,
sal DECIMAL(7,2),
comm DECIMAL(7,2),
deptno INT
) ;
INSERT INTO emp VALUES(7369,'SMITH','CLERK',7902,'1980-12-17',800,NULL,20);
INSERT INTO emp VALUES(7499,'ALLEN','SALESMAN',7698,'1981-02-20',1600,300,30);
INSERT INTO emp VALUES(7521,'WARD','SALESMAN',7698,'1981-02-22',1250,500,30);
INSERT INTO emp VALUES(7566,'JONES','MANAGER',7839,'1981-04-02',2975,NULL,20);
INSERT INTO emp VALUES(7654,'MARTIN','SALESMAN',7698,'1981-09-28',1250,1400,30);
INSERT INTO emp VALUES(7698,'BLAKE','MANAGER',7839,'1981-05-01',2850,NULL,30);
INSERT INTO emp VALUES(7782,'CLARK','MANAGER',7839,'1981-06-09',2450,NULL,10);
INSERT INTO emp VALUES(7788,'SCOTT','ANALYST',7566,'1987-04-19',3000,NULL,20);
INSERT INTO emp VALUES(7839,'KING','PRESIDENT',NULL,'1981-11-17',5000,NULL,10);
INSERT INTO emp VALUES(7844,'TURNER','SALESMAN',7698,'1981-09-08',1500,0,30);
INSERT INTO emp VALUES(7876,'ADAMS','CLERK',7788,'1987-05-23',1100,NULL,20);
INSERT INTO emp VALUES(7900,'JAMES','CLERK',7698,'1981-12-03',950,NULL,30);
INSERT INTO emp VALUES(7902,'FORD','ANALYST',7566,'1981-12-03',3000,NULL,20);
INSERT INTO emp VALUES(7934,'MILLER','CLERK',7782,'1982-01-23',1300,NULL,10);
CREATE TABLE dept(
deptno INT,
dname VARCHAR(14),
loc VARCHAR(13)
);
INSERT INTO dept VALUES(10, 'ACCOUNTING', 'NEW YORK');
INSERT INTO dept VALUES(20, 'RESEARCH', 'DALLAS');
INSERT INTO dept VALUES(30, 'SALES', 'CHICAGO');
INSERT INTO dept VALUES(40, 'OPERATIONS', 'BOSTON');
select * from emp where sal>(select avg(sal) from emp where deptno=10) and deptno!=10;
select * from emp where sal>(select max(sal) from emp where deptno=10) and deptno!=10;
select * from emp where (ename,job)in(select ename,job from emp where deptno=10) and deptno!=10;
select ename,dname from emp,dept where emp.deptno=dept.deptno;
select * from emp,(select distinct mgr from emp) m where emp.empno=m.mgr;
select * from emp where sal>(select avg(sal) from emp where deptno=10);
select deptno from emp group by deptno having avg(sal) > (select avg(sal) from emp where deptno=30);
select * from emp where sal>(select sal from emp where ename='JONES');
select * from emp where deptno=(select deptno from emp where ename='SCOTT') and ename!='SCOTT';
select * from emp where sal>(select max(sal) from emp where deptno=10) and deptno!=30;
select * from emp where (job,sal)in(select job,sal from emp where ename='MARTIN') and ename!='MARTIN';
select * from emp where empno in(select mgr from emp group by mgr having count(mgr)>2);
select ename,sal,dname,loc from emp,dept where empno=7788 and emp.deptno=dept.deptno;
select * from emp e where sal>(select avg(sal) from emp m group by deptno having e.deptno=m.deptno);
select * from emp where sal>(select avg(sal) from emp where deptno=(select deptno from dept where loc='NEW YORK')) and deptno=(select deptno from dept where loc='DALLAS');
select empno,ename,mgr,(select ename from emp where empno=7369) from emp where empno=7369;
select * from emp e where sal=(select max(sal) from emp m group by deptno having e.deptno=m.deptno);
CREATE TABLE test(
NAME CHAR(20),
kecheng CHAR(20),
fenshu CHAR(20)
);
INSERT INTO test VALUES('张三','语文',81),
('张三','数学',75),
('李四','语文',76),
('李四','数学',90),
('王五','语文',81),
('王五','数学',82);
select distinct name from test where fenshu > 80;