#创建表#

drop table if exists tb_user;

CREATE TABLE tb_user (

user_id VARCHAR(60) not null PRIMARY KEY,

user_name VARCHAR (60) not null,

user_level INT DEFAULT 1 not null,

user_password VARCHAR (100) not null,

user_email VARCHAR (50) NULL ,

user_sex bit DEFAULT 0 NULL,

user_age INT NULL

)

#额外添加主键#

Alter table tabname add primary key(col)

#添加外键#

alter table tb_user add constraint key_id foreign key(user_id) REFERENCES tb_stu(id)

#删除外键#

alter table tableName drop foreign key key_id

#插入#

insert into table1(field1,field2) values(value1,value2)

示例：insert into table_a(a) values("已连接")

#更新#

update table1 set field1=value1 where 条件

#删除#

delete from table1 where 范围

#查询#

select * from table1 where 范围

#参考链接#

https://www.cnblogs.com/jondam/p/6259666.html

https://www.cnblogs.com/yunf/archive/2011/04/12/2013448.html