1. create database yyzc; show database yyzc;z drop database yyzc;
2. show engines; show variables like ‘have %‘; Alter table user engine=myisam
3. mysql -h localhost -u root -p; enter passwork
4. 创建、修改和删除表
创建表
1). create table example_0(id int,name varchar(20),sex boolean);
2). create table example_1 (stu_id int primary key, stu_name varchar(20),stu_sex boolean);
3). create table example_2 (stu_id int,course_id int grade float,primary key(stu_id, course_id));
4). create table example_3 (id int primary key, stu_id int course_id int, Constraint c_fk foreign key(stu_id,course_id) references example_2(stu_id,course_id));
5). create table example_4 (id int not null primary key, name varchar(20) not null, stu_id int, Constraint d_fk foreign key(stu_id) references example_1(stu_id) );
6). create table example_5(id int primary key, stu_id int unique, name varchar(20) not null);
7). create table example_6(id int primary key, Auto_increment, stu_id int unique, name varchar(20) not null);
8). create table example_7(id int primary key, Auto_increment, stu_id int unique, name varchar(20) not null English varchar(20) default ‘zero‘, Math float default 0, Computer Float default 0); desc user show create table user
修改字段
1). alter table example rename user
2). alter table example modify name varchar(20)
3). alter table example change stu_name name varchar(20)
4). alter table example change stu_sex sex int(2)
增加字段
5). alter table user add phone varchar(20)
6). alter table user add age int(4) not null
7). alter table user add num int(4) primary key first
8). alter table user add address varchar(40) not null after phone
删除字段
9). alter table user drop id
10). alter table user modify name varchar(20) first
11). alter table user modify sex tinyint(1) after age
删除表外键约束
alter table example drop foregin key c_fk
删除表
1). dorp table example
2). alter table example drop foreign key d_fk, drop table example