完全外部自联接与不同日期的数据

Question

我想将值与第二天的值进行比较（还想查看哪种颜色是新的或未出现的）。

我已经完成了完全外部自连接并替换了“is_matched”右侧部分中的空值。 Is_matched 向我们展示了连接是否有效或右侧的部分在没有合并的情况下为空。

唯一的事情是最后一列“this_is_not_working”。 它应该具有“date_local2”的 total_colours 值，而不是“date_local”的值，我无法弄清楚如何用“this_is_not_working”列中的值替换所有空值。 我尝试过窗口函数和间隔，但并没有真正奏效。

我已经使用 Postgres 创建了这个db fiddle，但我使用的是 Presto。

select * from colours

date_local | colour | amount
:--------- | :----- | -----:
2020-01-01 | white  |     10
2020-01-01 | white  |     10
2020-01-01 | green  |     20
2020-01-01 | white  |     10
2020-01-01 | red    |     25
2020-01-01 | white  |     10
2020-01-02 | pink   |     15
2020-01-02 | pink   |     15
2020-01-02 | pink   |     15
2020-01-02 | pink   |     15
2020-01-02 | white  |     10
2020-01-02 | white  |     10
2020-01-02 | white  |     10
2020-01-02 | white  |     10
2020-01-02 | white  |     10
2020-01-03 | pink   |     15
2020-01-03 | pink   |     15
2020-01-03 | pink   |     15
2020-01-03 | green  |     20
2020-01-03 | green  |     20
2020-01-03 | green  |     20

with a as( 
    select
        *
        ,sum(colours) over(partition by date_local) as total_colour
    from ( 
        select 
            date_local
            ,colour
            ,count(colour) as colours 
            ,sum(amount) as amount 
        from colours
        group by 1,2
    ) as fr_om 
) 

select
    a.*
    ,b.date_local as is_matched
    ,coalesce(b.date_local, a.date_local + interval '1' day) as date_local_2
    ,coalesce(b.colour, a.colour) as colour_2
    ,coalesce(b.colours, 0) as colour_2
    ,coalesce(b.amount, 0) as amount_2
    ,coalesce(b.colours - a.colours, a.colours) as colour_difference
    ,coalesce(b.amount - a.amount, a.amount) as amount_difference
    ,b.total_colour as this_is_not_working
from a 
full outer join a as b 
    on a.date_local = b.date_local - interval '1' day 
    and a.colour = b.colour
order by 1

date_local | colour | colours | amount | total_colour | is_matched | date_local_2        | colour_2 | colour_2 | amount_2 | colour_difference | amount_difference | this_is_not_working
:--------- | :----- | ------: | -----: | -----------: | :--------- | :------------------ | :------- | -------: | -------: | ----------------: | ----------------: | ------------------:
2020-01-01 | red    |       1 |     25 |            6 | null       | 2020-01-02 00:00:00 | red      |        0 |        0 |                 1 |                25 |                null
2020-01-01 | green  |       1 |     20 |            6 | null       | 2020-01-02 00:00:00 | green    |        0 |        0 |                 1 |                20 |                null
2020-01-01 | white  |       4 |     40 |            6 | 2020-01-02 | 2020-01-02 00:00:00 | white    |        5 |       50 |                 1 |                10 |                   9
2020-01-02 | pink   |       4 |     60 |            9 | 2020-01-03 | 2020-01-03 00:00:00 | pink     |        3 |       45 |                -1 |               -15 |                   6
2020-01-02 | white  |       5 |     50 |            9 | null       | 2020-01-03 00:00:00 | white    |        0 |        0 |                 5 |                50 |                null
2020-01-03 | pink   |       3 |     45 |            6 | null       | 2020-01-04 00:00:00 | pink     |        0 |        0 |                 3 |                45 |                null
2020-01-03 | green  |       3 |     60 |            6 | null       | 2020-01-04 00:00:00 | green    |        0 |        0 |                 3 |                60 |                null
null       | null   |    null |   null |         null | 2020-01-02 | 2020-01-02 00:00:00 | pink     |        4 |       60 |              null |              null |                   9
null       | null   |    null |   null |         null | 2020-01-01 | 2020-01-01 00:00:00 | white    |        4 |       40 |              null |              null |                   6
null       | null   |    null |   null |         null | 2020-01-03 | 2020-01-03 00:00:00 | green    |        3 |       60 |              null |              null |                   6
null       | null   |    null |   null |         null | 2020-01-01 | 2020-01-01 00:00:00 | green    |        1 |       20 |              null |              null |                   6
null       | null   |    null |   null |         null | 2020-01-01 | 2020-01-01 00:00:00 | red      |        1 |       25 |              null |              null |                   6

Answer 1

我不认为你需要一个full join 。 窗口函数可以完成工作：

select 
    date_local,
    colour,
    no_colour,
    sum_amount,
    total_colour,
    is_matched,
    case when is_matched = 1
        then lead(date_local) over(partition by colour order by date_local)
    end date_local_2,
    case when is_matched = 1
        then lead(colour) over(partition by colour order by date_local) 
    end colour_2,
    case when is_matched = 1 
        then lead(no_colour) over(partition by colour order by date_local) 
    end no_colour_2,
    case when is_matched = 1 
        then lead(sum_amount) over(partition by colour order by date_local) 
    end sum_amount_2,
    case when is_matched = 1 
        then lead(total_colour) over(partition by colour order by date_local) 
    end total_colour_2  
from (
    select
        date_local,
        colour,
        count(*) no_colour,
        sum(amount) sum_amount,
        case when lead(date_local) over(partition by colour order by date_local) 
            = date_local + interval '1' day
            then 1
        end is_matched,
        sum(count(*)) over(partition by date_local) total_colour
    from colours
    group by date_local, colour
) t
order by date_local, colour

内部查询按天和颜色聚合，并计算组级指标以及每天的总记录数； 它还设置一个标志，指示第二天是否存在相同颜色的“相邻”记录。

然后，外部查询使用窗口函数lead()从相邻行中恢复值。

在您的 db fiddle 中，这会产生：

date_local | colour | no_colour | sum_amount | total_colour | is_matched | date_local_2 | colour_2 | no_colour_2 | sum_amount_2 | total_colour_2
:--------- | :----- | --------: | ---------: | -----------: | ---------: | :----------- | :------- | ----------: | -----------: | -------------:
2020-01-01 | green  |         1 |         20 |            6 |       null | null         | null     |        null |         null |           null
2020-01-01 | red    |         1 |         25 |            6 |       null | null         | null     |        null |         null |           null
2020-01-01 | white  |         4 |         40 |            6 |          1 | 2020-01-02   | white    |           5 |           50 |              9
2020-01-02 | pink   |         4 |         60 |            9 |          1 | 2020-01-03   | pink     |           3 |           45 |              6
2020-01-02 | white  |         5 |         50 |            9 |       null | null         | null     |        null |         null |           null
2020-01-03 | green  |         3 |         60 |            6 |       null | null         | null     |        null |         null |           null
2020-01-03 | pink   |         3 |         45 |            6 |       null | null         | null     |        null |         null |           null