从两个表中获取字段的总和和差异

Question

I have two tables

1. sales:

sale_date	total_amount
2021-03-24	59000
2021-03-24	25000
2021-03-25	88000
2021-03-25	10000
2021-03-26	67000
2021-03-27	99000

2. credit_sales:

credit_sale_date	amount
2021-03-24	10000
2021-03-24	2000
2021-03-24	3000
2021-03-25	1000
2021-03-25	5000
2021-03-25	6000
2021-03-26	22000
2021-03-27	15000

Expected Result:

date	total_amount	cash_amount	credit_amount
2021-03-24
2021-03-25
2021-03-26
2021-03-27

total_amount is the sum of 'total_amount' from sales table of a particular date

credit_amount = sum of 'amount' from credit_sales table of the particular date

cash_amount = sum of 'total_amount' from sales table - sum of 'amount' from credit_sales table of the particular date

Answer 1

select
    sale_date as date, sum(DISTINCT total_amount) as total_amount, sum(DISTINCT amount) as credit_amount, sum(DISTINCT total_amount) + sum(DISTINCT amount) as cash_amount
from
    sales, credit_sales
where 
    sales.sale_date = credit_sales.credit_sale_date
GROUP BY sales.sale_date

Answer 2

Union and group

select sale_date, sum(total_amount) as total_amount,
   sum(credit_amount) as credit_amount,
   sum(total_amount) - sum(credit_amount) as cash_amount
from (
    select sale_date, total_amount, 0 as credit_amount
    from sales 
    union all
    select credit_sale_date, 0 as total_amount, amount as credit_amount
    from credit_sales
) t
group by sale_date