PostgreSQL - 使用另一个 table 的先前值更新 table

Question

我想更新 table 一秒的总和 table

这是我要更新的 table 'x'。有起始值和结束值：

id	op_date	initial_value	end_value
1	2020-02-01	0	0
1	2020-02-02	0	0
2	2020-02-01	0	0
2	2020-02-02	0	0

table'y'保存当天的数值：

id	op_date	value_day
1	2020-01-29	500
1	2020-02-01	100
1	2020-02-02	200
2	2020-01-29	750
2	2020-02-01	100
2	2020-02-02	250

我希望结果如下所示：

id	op_date	initial_value	end_value
1	2020-02-01	500	600
1	2020-02-02	600	800
2	2020-02-01	750	850
2	2020-02-02	850	1100

我试过这个脚本，但是进程只是运行它而没有完成它：

UPDATE x
SET 
    initial_value= (select sum(y.value_day) 
        from public.y where 
        y.op_date > '2020-11-01' and y.op_date < x.op_date 
        and y.id = x.id),
    end_value= (select sum(y.value_day) 
        from public.y where 
        y.op_date between '2020-11-01' and x.op_date 
        and y.id = x.id);

Answer 1

您可以使用window函数。要进一步了解 window 功能，您可以查看此 link。 起初我正在写查询 select 值。

select id,op_date,
sum(value_day) over (
    partition by y.id   
    rows between unbounded preceding and current row
  )-value_day as initial_value,
sum(value_day) over (
    partition by y.id   
    rows between unbounded preceding and current row
  ) as end_value
from y

;

这是您的更新查询。

UPDATE x
set initial_value=s_statement.initial_value,
end_value=s_statement.end_value
from 
(select id,op_date,
sum(value_day) over (
    partition by y.id    
    rows between unbounded preceding and current row
  )-value_day as initial_value,
sum(value_day) over (
    partition by y.id   
    rows between unbounded preceding and current row
  ) as end_value
from y) s_statement
where x.id=s_statement.id 
and x.op_date=s_statement.op_date

;

让我知道你是否满意。