Mysql数据库的应用!!!
1.sql语句的应用:
create table student (
id int not null,
name varchar(20) not null,
age varchar(20) not null,
sex varchar(20) not null,
primary key(id)
);
create table teacher(
id int not null,
name varchar(20),
course varchar(20),
student_id int,
primary key(id),
constraint foreign key(student_id) references student(id)
);
insert into student values(1,"ka","30","nan");
insert into teacher values(1,"zy","java",2);
update
2.数据库关系的设计(重点)
一对一
多对一
多对多
主键和外键的建立
多对多:
通过建立中间表实现!!!
3.数据库的导入导出命令
4.主外键的定义
PRIMARY KEY(id), CONSTRAINT FOREIGN KEY(flight_id) REFERENCES flight
primary key(id), constraint foreign key(flight_id) references filght(id)
ALTER TABLE customer ADD CONSTRAINT customer_fk FOREIGN KEY(address_id) REFERENCES address(id);
constraint 约束 references提及
5. 事务
innodb 支持事务的
type=innodb;
6.查询的使用
select*from table;//查询表里所有列所有行!!
select columnName1,columnName2 from table;查询表里 指定的列
select distinct columnName from table;distinct去除重复的值
字符或日期应该放在" "或' '里