sql - 多个表的sql连接查询

Question

我有以下表格结构，

客户信息：

  cust_id   cust_name
  1           nikhil
  2           sam

账单信息：

 bill_id  cust_id   bill_amount 
    7         1     10000
    8         1     15000
    9         2     6000
    10        2     4000

付费信息：

   paid_id      cust_id  paid_amount  
      11         1        5000
      12         1        5000
      13         2        5000
      14         2        5000

现在我的输出应该显示客户支付的账单总和以及该客户支付的总金额和余额

输出

  cust_id   total_bill   total_paid  balance
    1        25000         10000      15000
    2        10000          10000       0

例如，对于 cust_id = 2，

 total_bill= 10000 + 15000
 total_paid = 5000 + 5000
 balance = total_bill - total_paid

在sql中执行此操作的便捷方法是什么？任何示例查询？

这是我已经尝试过的

SELECT distinct c.cust_id
    , sum(b.bill_amount) as total_bill
    , SUM(p.paid_amt) AS totalpaid,sum(b.bill_amount) - SUM(p.paid_amt) AS balance 
FROM cust_info c 
INNER JOIN bill_info b ON c.cust_id = b.cust_id 
INNER JOIN paid_info p ON p.cust_id= b.cust_id group by p.cust_id;

Answer 1

SELECT 
    cust_info.cust_id,
    cust_name,
    bill_amount,
    paid_amount,
    bill_amount - paid_amount AS balance
FROM cust_info
INNER JOIN (
    SELECT cust_id, SUM(bill_amount) bill_amount
    FROM bill_info
    GROUP BY cust_id
) bill_info ON bill_info.cust_id = cust_info.cust_id
INNER JOIN (
    SELECT cust_id, SUM(paid_amount) paid_amount
    FROM paid_info
    GROUP BY cust_id
) paid_info ON paid_info.cust_id = cust_info.cust_id

演示

Answer 2

SELECT c.cust_id,
       SUM(b.total_bill),
       SUM(p.total_paid),
       SUM(c.total_bill) - SUM(p.total_paid)
FROM
    cust_info c
    LEFT JOIN bill_info b ON (c.cust_id = b.cust_id)
    LEFT JOIN paid_info p ON (c.cust_id = p.party_id)
GROUP
    BY cust_info.cust_id

Answer 3

SELECT DISTINCT cust_info.cust_id,
                sum(bill_amount) AS 'total_bill' ,
                sum(paid_amount) AS 'total paid' ,
                (SUM(bill_amount) - sum(paid_amount)) AS balance
FROM cust_info
INNER JOIN bill_info ON cust_info.cust_id = bill_info.cust_id
INNER JOIN paid_info ON cust_info.cust_id = paid_info.cust_id
GROUP BY cust_info.cust_id