sql 加入时加入

Question

事务表（1 行 --> 1 个事务）

customer_code amount
A0BEFG        100
DEC21A        80

支付表（1 行 --> 1 笔交易）

customer_id   payment_type
1             cash
2             credit_card

客户表（1 行 --> 1 个客户代码）

customer_code    customer_id
A0BEFG           2
DEC21A           1

预期输出： 组合表

customer_code customer_id amount payment_type
AOBEFG        2           100    credit_card
DEC21A        1           80     cash       

也就是说，我的想法是把payment_type放到transactions表中，但是因为没有匹配变量，所以我需要先合并payment表和customer表，然后再连接到transactions表。

我试过的代码：

  with 
        connection as (
        select c.customer_code, c.customer_id, p. payment_type
        from data.payment p
        left join data.customer c on p.customer_id = c.customer_id 
    ),
        transactions as (
        select t.merchant_code, t.amount
        from data.transactions t
        )
    select 
        t.merchant_code, c.customer_id, c.amount, p.payment_type 
    from transactions as t

代码用于 PostgreSQL。

Answer 1

SELECT c.customer_code, c.customer_id, t.amount, p.payment_type
FROM customer AS c
INNER JOIN payment AS p ON p.customer_id = c.customer_id
INNER JOIN transactions AS t ON t.customer_code = c.customer_code

Answer 2

像这样将customer 加入其他表：

SELECT c.customer_code, c.customer_id, t.amount, p.payment_type
FROM transactions t
INNER JOIN customer c ON t.customer_code = c.customer_code
INNER JOIN payment p ON p.customer_id = c.customer_id

请参阅demo。
结果：

customer_code	customer_id	amount	payment_type
A0BEFG	2	100	credit_card
DEC21A	1	80	cash