将数据插入 Table 使用条件

Question

我有这两个table

daily_info

date	id	name	place
2022-04-11	1	Jhon	null
2022-04-12	1	Jhon	null
2022-04-13	1	Jhon	null
2022-04-14	1	Jhon	null
2022-04-15	1	Jhon	null
2022-04-16	1	Jhon	null

change_values

date	id	change_col	new_value
2022-04-14	1	place	Chicago
2022-04-16	1	place	India
2022-04-16	1	name	John watts

从这两个 table 中，我想创建一个新的 table，看起来像这样

history_table

date	id	name	place
2022-04-11	1	Jhon	null
2022-04-12	1	Jhon	null
2022-04-13	1	Jhon	null
2022-04-14	1	Jhon	Chicago
2022-04-15	1	Jhon	Chicago
2022-04-16	1	Jhon Watts	India

到目前为止我只能加入这两个 tables 并尝试使用 case-when 子句，我知道我需要使用滞后但我不是确定如何

我的代码

Select id, 
    date,
    (Case When change_col = 'place' Then new_value End) As place,
    (Case When change_col = 'name' Then new_value End) As name
From daily_info
Left Join change_values On d.id = c.id And d.date = c.date

Answer 1

根据日期加入（应用）您更改table，每种更改类型一次。

declare @daily_info table ([date] date, id int, [name] varchar(32), place varchar(32));

insert into @daily_info ([date], id, [name], place)
values
('2022-04-11', 1, 'Jhon', null),
('2022-04-12', 1, 'Jhon', null),
('2022-04-13', 1, 'Jhon', null),
('2022-04-14', 1, 'Jhon', null),
('2022-04-15', 1, 'Jhon', null),
('2022-04-16', 1, 'Jhon', null);

declare @change_values table ([date] date, id int, change_col varchar(32), new_value varchar(32));

insert into @change_values ([date], id, change_col, new_value)
values
('2022-04-14', 1, 'place', 'Chicago'),
('2022-04-16', 1, 'place', 'India'),
('2022-04-16', 1, 'name',  'John,Dan');

select DI.[date], DI.id
    , coalesce(CV2.new_value, DI.[name]) [name]
    , coalesce(CV1.new_value, DI.place) place
from @daily_info DI
outer apply (
    select top 1 change_col, new_value
    from @change_values CV
    where CV.[date] <= DI.[date] and change_col = 'place'
    order by [date] desc
) CV1
outer apply (
    select top 1 change_col, new_value
    from @change_values CV
    where CV.[date] <= DI.[date] and change_col = 'name'
    order by [date] desc
) CV2;

Returns:

date	id	name	place
2022-04-11	1	Jhon	NULL
2022-04-12	1	Jhon	NULL
2022-04-13	1	Jhon	NULL
2022-04-14	1	Jhon	Chicago
2022-04-15	1	Jhon	Chicago
2022-04-16	1	John,Dan	India

将数据插入 Table 使用条件

Insert Data Into a Table Using Condition

sql

sql-server

create-table