08mysql之创建和管理表

#1. 创建数据库test01_office,指明字符集为utf8。并在此数据库下执行下述操作
CREATE DATABASE IF NOT EXISTS test01_office CHARACTER SET 'utf8';

USE test01_office

#2. 创建表dept01
/*
字段 类型
id INT(7)
NAME VARCHAR(25)
*/
CREATE TABLE IF NOT EXISTS dept01(
id INT(7),
NAME VARCHAR(25)
);
#3. 将表departments中的数据插入新表dept02中
CREATE TABLE dept02
AS
SELECT *
FROM  atguigudb.departments;

SELECT *
FROM depart
#4. 创建表emp01
/*
字段 类型
id INT(7)
first_name VARCHAR (25)
last_name VARCHAR(25)
dept_id INT(7)
*/

CREATE TABLE empo1(
id INT(7),
first_name VARCHAR (25),
last_name VARCHAR (25),
dept_id int(7)
);

#5. 将列last_name的长度增加到50
desc empo1

alter table empo1
modify last_name varchar(50);

#6. 根据表employees创建emp02
create table emp02
as
select *
from atguigudb.`employees`;

show tables from test01_office;

#7. 删除表emp01

drop table empo1;

#8. 将表emp02重命名为emp01
#alter table emp02 rename to emp01;

rename table emp02 to emp01;

#9.在表dept02和emp01中添加新列test_column，并检查所作的操作

alter table emp01 add test_colunm varchar(10);

desc emp01;

alter table dept02 add test_colunm varchar(10);

desc dept02;

#10.直接删除表emp01中的列 department_id

alter table emp01
drop column department_id;

#练习2：
# 1、创建数据库 test02_market

create database if not exists test02_masket character set 'utf8';

use test02_masket

show create database test02_masket
# 2、创建数据表 customers
create table if not exists customers(
c_num int,
c_name varchar(50),
c_contact varchar(50),
c_city varchar(50),
c_birth date);

show tables;

# 3、将 c_contact 字段移动到 c_birth 字段后面
desc customers;

alter table customers
modify c_contact varchar(50) after c_birth;

# 4、将 c_name 字段数据类型改为 varchar(70)

alter table customers
modify c_name varchar(70);

# 5、将c_contact字段改名为c_phone
alter table customers
change c_contact c_phone varchar(50)

# 6、增加c_gender字段到c_name后面，数据类型为char(1)
alter table customers
add c_gender char(1) after c_name;

# 7、将表名改为customers_info
rename table customers
to customers_info

desc customers_info
# 8、删除字段c_city
alter table customers_info
drop column c_city

#练习3:
# 1、创建数据库test03_company
create database if not exists test03_company character set 'utf8'

use test03_company

# 2、创建表offices
create table if not exists office(
officeCode int,
city varchar(30),
address varchar(50),
country varchar(50),
postalCode varchar(25)
);

desc  offices;

rename table office
to offices

# 3、创建表employees
create table if not exists employees(
empNum int,
lastName varchar(50),
firstname varchar(50),
mobile int,
`code` int,
jobTitle varchar(50),
birth date,
note varchar(255),
sex varchar(5)
);

desc employees;

# 4、将表employees的mobile字段修改到code字段后面
alter table employees
modify mobile varchar(20) after `code`;

# 5、将表employees的birth字段改名为birthday
alter table employees
change birth birthday date;

# 6、修改sex字段，数据类型为char(1)

alter table employees
modify sex char(1);

# 7、删除字段note
alter table employees
drop column note;

# 8、增加字段名favoriate_activity，数据类型为varchar(100)
alter table employees
add favoriate_activity varchar(100);

# 9、将表employees的名称修改为 employees_info
rename table employees to employees_into
desc employees_into