将另一个组添加到递归 CTE 中 [英] Adding a further group into a recursive CTE

问题描述

参考这个 .新的Sql Fiddle.

Referring back to this SO post

If there is a Grouping category "Category" which, for simplicity's sake, can be either X or Y - is it a trivial matter amending this script so that it will add in the missing dates for each of the categories ?

I assume the category will need adding into the CTE?

In other words if I have the following initial table:

...how do I get to the following:

Will upload my attempt shortly

I've called the initial table #x. I'm hoping to adapt a recursive CTE query like the following to include the field Category:

DECLARE @MinDate DATETIME; 
SET @MinDate =  (SELECT Min(DATE) FROM #x)

DECLARE @MaxDate DATETIME; 
SET @MaxDate =  (SELECT Max(DATE) FROM #x)

;WITH times AS 
    ( 
    SELECT @MinDate dt , 1 depth 
    UNION ALL 
    SELECT 
            DATEADD(d, depth, @MinDate) dt 
            , 1 + depth as depth 
    FROM times 
    WHERE DATEADD(d, depth, @MinDate) <= @MaxDate
    ) 
SELECT 
    * 
FROM 
    TIMES t
    LEFT OUTER JOIN #X x
        ON 
        t.dt = x.Date

Ok - I've tied including a CROSS JOIN but it expands things incorrectly:

SELECT DISTINCT Category INTO #Cat FROM #x

DECLARE @MinDate DATETIME; 
SET @MinDate =  (SELECT Min(DATE) FROM #x)

DECLARE @MaxDate DATETIME; 
SET @MaxDate =  (SELECT Max(DATE) FROM #x)


;WITH times AS 
    ( 
    SELECT 
            Category
            , @MinDate dt 
            , 1 depth 
    FROM #Cat
    UNION ALL 
    SELECT 
            c.Category
            , DATEADD(d, depth, @MinDate) dt 
            , 1 + depth as depth 
    FROM 
            times t
            CROSS JOIN #Cat c
                --ON c.Category IS NOT NULL
    WHERE DATEADD(d, depth, @MinDate) <= @MaxDate
    ) 
SELECT 
    * 
FROM 
    TIMES

This seems to have worked ok:

SELECT DISTINCT Category INTO #Cat FROM #x

DECLARE @MinDate DATETIME; 
SET @MinDate =  (SELECT Min(DATE) FROM #x)

DECLARE @MaxDate DATETIME; 
SET @MaxDate =  (SELECT Max(DATE) FROM #x)


;WITH times AS 
    ( 
    SELECT 
            Category
            , @MinDate dt 
            , 1 depth 
    FROM #Cat
    UNION ALL 
    SELECT 
            Category
            , DATEADD(d, depth, @MinDate) dt 
            , 1 + depth as depth 
    FROM 
            times t
    WHERE DATEADD(d, depth, @MinDate) <= @MaxDate
    ) 
SELECT 
    * 
FROM 
    TIMES

解决方案

Here is a solution without a calendar table (which is a must in production). You might have date range in variables, or you might go for min() and max() from the_table.

EDIT: shorter version incorporating categories into date range generation

declare @startdate datetime = '2012-1-1'
declare @enddate datetime = '2012-1-5'

; with dates([date], category) as (
  select distinct @startdate, category
    from the_table
   union all
  select dateadd (day, 1, [date]), category
    from dates
   where [date] < @enddate
)
select dates.date, 
       dates.category, 
       isnull(the_table.amount, 0) Amount
  from dates
  left join the_table
    on dates.date = the_table.date
   and dates.category = the_table.category
 order by dates.category, dates.date
option (maxrecursion 0)

There is live test @ Sql Fiddle. New Sql Fiddle.

这篇关于将另一个组添加到递归 CTE 中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！