使用另一个查询中一列的所有值

I am trying to find a solution for the following issue that I have in sql-server:

我正在尝试找到我在sql-server中遇到的以下问题的解决方案:

I have one table t1 of which I want to use each date for each agency and loop it through the query to find out the avg_rate. Here is my table t1:

我有一个表t1,其中我想使用每个代理的每个日期,并通过查询循环以找出avg_rate。这是我的表t1:

Table T1:

+--------+-------------+
| agency |  end_date   |
+--------+-------------+
|      1 | 2017-10-01  |
|      2 | 2018-01-01  |
|      3 | 2018-05-01  |
|      4 | 2012-01-01  |
|      5 | 2018-04-01  |
|      6 | 2017-12-01l |
+--------+-------------+

I literally want to use all values in the column end_date and plug it into the query here (I marked it with ** **):

我真的想要使用end_date列中的所有值并将其插入到查询中(我用** **标记它):

    with averages as (
select      a.id as agency
            ,c.rate  
            , avg(c.rate) over (partition by a.id  order by a.id )  as avg_cost


from table_a as a
                     join  rates c on a.rate_id = c.id


and c.end_date =  **here I use all values from t1.end_date** 
and c.Start_date =  **here I use all values from above minus half a year** = dateadd(month,-6,end_date)

group by    a.id 
            ,c.rate  
            )
select distinct agency, avg_cost  from averages 
order by 1

The reason why I need two dynamic dates is that the avg_rates vary if you change the timeframe between these dates.

我需要两个动态日期的原因是,如果您更改这些日期之间的时间范围,avg_rates会有所不同。

My problem and my question is now:

我的问题和我的问题现在是:

How can you take the end_date from table t1 plug it into the query where c.end_date is and loop if through all values in t1.end_date?

如何从表t1中取出end_date将其插入到c.end_date所在的查询中,如果通过t1.end_date中的所有值,则循环它?

I appreciate your help!

我感谢您的帮助!

2 个解决方案

#1

I can think of several ways to do this - Cursor, StoredProcedure, Joins ... Given the simplicity of your query, a cartesian product (Cross Join) of Table T1 against the averages CTE should do the magic.

我可以想到几种方法 - Cursor,StoredProcedure,Joins ...鉴于查询的简单性,表T1的平面CTE的笛卡尔积(交叉连接)应该具有魔力。

#2

Do you really need a windowed average? Try this out.

你真的需要平均窗口吗?试试吧。

;with timeRanges AS
(
    SELECT
        T.end_date,
        start_date = dateadd(month,-6, T.end_date)
    FROM
        T1 AS T
)
select      
    a.id as agency,
    c.rate,
    T.end_date,
    T.start_date,
    avg_cost = avg(c.rate)
from 
    table_a as a
    join  rates c on a.rate_id = c.id
    join timeRanges AS T ON A.DateColumn BETWEEN T.start_date AND T.end_date
group by   
    a.id ,
    c.rate,
    T.end_date,
    T.start_date

You need a date column to join your data against T1 (I called it DateColumn in this example), otherwise all time ranges would return the same averages.

您需要一个日期列来将您的数据与T1连接(在本例中我称之为DateColumn),否则所有时间范围都将返回相同的平均值。

#1