小编ope*_*enV的帖子

我需要帮助创建一个SQL查询来计算在两个单独的列上分解的行.

这是我的表的DDL:

CREATE TABLE Agency (
  id SERIAL not null,
  city VARCHAR(200) not null,
  PRIMARY KEY(id)
);
CREATE TABLE Customer (
  id SERIAL not null,
  fullname VARCHAR(200) not null,
  status VARCHAR(15) not null CHECK(status IN ('new','regular','gold')),
  agencyID INTEGER not null REFERENCES Agency(id),
  PRIMARY KEY(id)
);

表格中的样本数据

AGENCY
id|'city'
1 |'London'
2 |'Moscow'
3 |'Beijing'

CUSTOMER
id|'fullname'      |'status' |agencyid
1 |'Michael Smith' |'new'    |1
2 |'John Doe'      |'regular'|1
3 |'Vlad Atanasov' |'new'    |2
4 |'Vasili Karasev'|'regular'|2
5 |'Elena Miskova' |'gold'   |2 …