数据库课程作业，使用 java 实现的一个 DBMS

• 用户登录

  语句格式: login username password
  例句: login root 123

• 用户退出

  语法格式: exit

• 选择数据库

  语法格式: use database_name
  例句: use db1

• 创建数据库

  语法格式: create database database_name
  例句: create database db2

• 创建用户

  语法格式: create user username password
  例句: create user user1 123

• 创建基本表

  语法格式: create table table_name (属性名 属性类型 约束条件)
  例句: create table student (sno varchar, name varchar, score int)

• 创建视图

  语法格式: create view view_name as select 属性名1, 属性名2…from table table_name
  例句: create view vstudent as select name , grade from student

• 删除数据库

  语法格式: drop database database_name
  例句: drop database db2

• 删除用户

  语法格式: drop user user_name
  例句: drop user user1

• 删除基本表

  语法格式: drop table table_name
  例句: drop table t1

• 删除视图

  语法格式: drop view view_name
  例句: drop view v_student

语法格式: insert into table_name values(value1, value2, value3)
例句: insert into student  values(“61428”, “wsl”, 88)

• 不带where子句

  语法格式: delete from table_name
  例句: delete from student

• 带有where子句

  语法格式: delete from table_name where 条件1 (and || or) 条件2 …
  例句: delete from student where name != ”wsl” and  name !=”hp”

• 不带where子句

  语法格式: update table_name set 属性1 = 值1, 属性2 = 值2…
  例句: upodate student set score = 90

• 带有where子句

  语法格式: update table_name set 属性1 = 值1, 属性2 = 值2… where 条件1 (and || or) 条件2 …
  例句: update student set name = "zs", score = 95 where name = "wsl"

• 查看所有的数据

  语法格式: select * from table_name
  例句: select * from student

• 查看符合where子句条件的数据

  语法格式: select * from table_name where 条件1(and || or) 条件2…
  例句: select * from student where name = "ls" or name = "zl"

• 对结果集排序

  语法格式: select * from table_name [where 条件1(and || or) 条件2…] order by 属性1 (asc || desc)
  例句: select * from student where score > 60 order by sno asc

• 聚集函数的使用

  语法格式: select count||avg||sum||min||max (属性名) from table_name where 条件1(and || or) 条件2…
  例句1: select sum(score) from student
  例句2: select avg(score) from student
  例句3: select max(score) from student
  例句4: select min(score) from student
  例句5: select count(score) from student

• 查询指定列的数据

  语法格式: select属性名1，属性2… from table_name (where 条件1(and || or) 条件2…)
  例句: select sno, name from student where score > 60

• 授予权限

  语法格式: grant (all privileges) || (select, delete …) on table t1, t2 … to user1, user2 …
  例句1: grant select , delete , update on table student , t1 to user1, user2
  例句2: grant all privileges on table t1 to u1

• 收回权限

  语法格式: revoke (all privileges) || (select, delete …) on table t1, t2 … from user1, user2 …
  例句1: revoke delete , update on table student from user1
  例句2: revoke all privileges on table t1 from u1

• 输出当前数据库下所有的表和视图的信息

  语法格式: help database
  例句: help database

• 输出指定基本表的详细信息

  语法格式: help table table_name
  例句: help table student

• 输出指定视图的详细信息

  语法格式: help view view_name
  例句: help view v_student