-- 创建序列号（如果存在则先删除再创建）
declare 
    num number; 
begin 
    select count(0) into num from user_sequences where sequence_name ='SEQ_USER_ID'; 
    if num>0 then 
        execute immediate 'drop sequence SEQ_USER_ID'; 
    end if; 
end; 
/

create sequence SEQ_USER_ID
minvalue 1
maxvalue 99999999999
start with 1
increment by 1;

-- 创建数据库表（如果存在则先删除再创建）
declare 
    num number; 
begin 
    select count(0) into num from all_tables where TABLE_NAME='MS_USER'; 
    if num>0 then 
        execute immediate 'drop table MS_USER'; 
    end if; 
end; 
/

create table MS_USER(
  user_id number(11) not null primary key,mobile_phone varchar2(16) not null,user_name varchar2(32) not null
);

-- 增加数据库表备注和表字段的备注信息
comment on table MS_USER is '用户信息表';
comment on column MS_USER.user_id is '用户ID';
comment on column MS_USER.mobile_phone is '手机号码';
comment on column MS_USER.user_name is '用户名称';

-- 增加索引
create unique index index_mobile_phone on MS_USER(mobile_phone);
create index index_user_name on MS_USER(user_name);