회원가입 위한 DB 생성 및 수정 쿼리문

create table category(
    category_no number primary key,
    category_name varchar2(50));
insert into category values(1,'IT');
insert into category values(2,'영어');
select * from category;

create table user_info(
  user_no varchar2(100) primary key,
  category_no number,
  user_id varchar2(50) unique,
  user_pw varchar2(50),
  user_phoneNo varchar2(12),
  user_birth varchar2(10),
  user_email varchar2(50),
  user_register_date date);
  
create sequence user_seq;

alter table user_info
  add (user_name varchar(20));

select * from user_info;

alter table user_info
  add constraint user_category_no_fk foreign key(category_no)
  references category(category_no);
  
alter table user_info
  modify user_birth varchar2(20);
  
  
--회원아이디 중복확인을 위한 COUNT 코드 0
SELECT COUNT(*) FROM USER_INFO WHERE USER_ID='';