qq_45396088的博客

//添加普通索引 CREATE index economy_organization_id on economy_organization(id) //添加非空索引 CREATE UNIQUE INDEX economy_organization_id ON economy_organization (id) ; //添加主键索引 CREATE PRIMARY INDEX economy_organization_id ON economy_organization (id) ; //删除索引 drop

//起别名 SELECT `id` 账号,`title` 姓名 from edu_chapter; //去重 SELECT DISTINCT teacher_id from edu_comment; //将id和nickname两个字段拼接，并起别名 SELECT CONCAT(id,nickname) as 姓名 from edu_comment //模糊查询的两种方式 SELECT DISTINCT * from edu_comment WHERE nickname LIKE '%1%' SELEC

//登录MySQL数据库localhost是打开数据的地址 3306是MySQL的使用端口号 root是账号 123456是密码 mysql -h localhost -P 3306 -u root -p123456 //打开所有的库 show databases; //打开tp_music表 use tp_music //展示数据库里的tp_music表 show tables from tp_music //查看打开的库 select database(); //创建表 test是表名 create t