Mysql常用语句部分(1)

create database oa;//创建数据库 drop database oa;//删除数据库 use oa;//使用数据库 alter table zhulei add column createTime timestamp default CURRENT_TIMESTAMP; //给表添加属性 alter table person modify id int AUTO_INCREMENT;//修改表属性 添加自动增长列 alter table person modify name varchar(40) UNIQUE ;//添加唯一属性 insert into person(name,sex) values('zhulei','男');//插入数据 update person set sex='女'//更新所有数据 alter table person modify sex enum('男','女');//添加枚举类型 alter table person add age int after sex;//在sex之后添加属性 之前first create table users( id int primary key, username varchar(20) not null, userpass varchar(20) not null, preson_id int foreign key (person_id) REFERENCES person(id)); //创建时添加外键属性 create table users_temp( id int primary key, username varchar(20) not null, userpass varchar(20) not null, createTime TIMESTAMP default CURRENT_TIMESTAMP, person_id int , KEY `person` (`person_id`), CONSTRAINT `person` FOREIGN KEY (`person_id`) REFERENCES `person` (`id`)); create table users_temp( id int primary key, username varchar(20) not null, userpass varchar(20) not null, createTime TIMESTAMP default CURRENT_TIMESTAMP, person_id int , index `person` (`person_id`), CONSTRAINT `person` FOREIGN KEY (`person_id`) REFERENCES `person` (`id`));//注意索引必须不能相同 select * from person p join users u on u.person_id=p.id;//连接查询 select * from person p left join users u on u.person_id=p.id;//左连接 select * from person p right join users u on u.person_id=p.id;//右连接 show create table users; //显示创建的语句 DROP TABLE IF EXISTS `dept`;//删除表中数据 create table dept( deptNo varchar(40) primary key , name varchar(40) not null, createDeptTimes timestamp, managerNo varchar(40), PRIMARY KEY (deptNo), index manager (managerNo), CONSTRAINT manager FOREIGN KEY (managerNo) REFERENCES emp (empNo));