Question

我的SQL Server有一个表。两列都是整数，但以YYYYMM的形式表示日期。我想查询该表并返回第三列，该列的每一行每一年/每个月在这两列的范围内都包括一个YYYYMM形式的整数。

这是表格：

+------------+------------+
| beg_YYYYMM | end_YYYYMM |
+------------+------------+
|     201802 |     201805 |
|     201711 |     201801 |
+------------+------------+

所需的输出：

+------------+------------+----------------+
| beg_YYYYMM | end_YYYYMM | month_in_range |
+------------+------------+----------------+
|     201802 |     201805 |         201802 |
|     201802 |     201805 |         201803 |
|     201802 |     201805 |         201804 |
|     201802 |     201805 |         201805 |
|     201711 |     201801 |         201711 |
|     201711 |     201801 |         201712 |
|     201711 |     201801 |         201801 |
+------------+------------+----------------+

Answer 1

使用递归CTE：

with cte as (
      select beg_YYYYMM, end_YYYYMM,
             convert(date, convert(varchar(255), beg_YYYYMM) + '01') as dte,
             convert(date, convert(varchar(255), end_YYYYMM) + '01') as end_dte
      from t
      union all
      select beg_YYYYMM, end_YYYYMM,
             dateadd(month, 1, dte),
             end_dte
      from cte
      where dte < end_dte
     )
select beg_yyyymm, end_yyyymm, 
       year(dte) * 100 + month(dte) as yyyymm
  from cte
 order by dte;

Here是db <>小提琴。

Answer 2

我真的不认为我会实际部署它，但我想知道它的外观。如果创建的TVF做得很丑，那还不错。我使用Aaron Bertrand的DateDim code进行了快速修改，以仅获取传入的两个日期之间的月份日期。

CREATE OR ALTER FUNCTION dbo.tvf_MonthRange (@beg_YYYYMM int, @end_YYYYMM int)  
RETURNS @Results TABLE   
 (month_in_range int)
AS  
BEGIN  

--Have to convert ints to dates
    DECLARE @BegDate DATE; 
    SET @BegDate =  DATEFROMPARTS(CAST(SUBSTRING(CAST(@beg_YYYYMM AS varchar(6)),1,4) AS INT), CAST(SUBSTRING(CAST(@beg_YYYYMM AS varchar(6)),5,2) AS INT), 1);

--This needs to be the second day of the month for the code below to work.
    DECLARE @EndDate DATE;
    SET @EndDate =  DATEFROMPARTS(CAST(SUBSTRING(CAST(@end_YYYYMM AS varchar(6)),1,4) AS INT), CAST(SUBSTRING(CAST(@end_YYYYMM AS varchar(6)),5,2) AS INT), 2);

    INSERT INTO @Results
    SELECT (DATEPART(YEAR, d) *100) + DATEPART(MONTH, d)
    FROM
        (
          SELECT d = DATEADD(DAY, rn - 1, @BegDate)
          FROM 
          (
            SELECT TOP (DATEDIFF(DAY, @BegDate, @EndDate)) 
              rn = ROW_NUMBER() OVER (ORDER BY s1.[object_id])
            FROM sys.all_objects AS s1
            CROSS JOIN sys.all_objects AS s2
            -- on my system this would support > 5 million days
            ORDER BY s1.[object_id]
          ) AS x
        ) AS y
    WHERE DATEPART(DAY, d) = 1;

    RETURN;
END

然后您可以这样称呼它。

DECLARE @Months TABLE (beg_YYYYMM int, end_YYYYMM int)
INSERT INTO @MONTHS SELECT 201802, 201805 
INSERT INTO @MONTHS SELECT 201711, 201801 

SELECT *
FROM @Months m
CROSS APPLY dbo.tvf_MonthRange(m.beg_YYYYMM, m.end_YYYYMM) mr ;

星期一不好主意吧？

Answer 3

使用计数表的解决方案，在较大的数据集上可能更快。

with dates as(
select 
    201501 as beg_YYYYMM
    ,201504 as end_YYYYMM
union all
select '201711', '201801'
union all
select '201807', '201812'

),

--Tally table
ctedaterange AS (
SELECT top 15
    rn = Row_number() OVER(ORDER BY (SELECT NULL)) -1
FROM sys.objects a  
)

SELECT
    dates.*
    ,months_in_range = convert(varchar(6), Dateadd(mm, rn, cast(cast(dates.beg_YYYYMM as varchar(8)) +'01' as date)), 112)

FROM dates
    cross join ctedaterange

WHERE  
    rn <= Datediff(mm, cast(cast(dates.beg_YYYYMM as varchar(8)) +'01' as date), cast(cast(dates.end_YYYYMM as varchar(8)) +'01' as date))

ORDER BY 
    beg_YYYYMM
    ,Dateadd(mm, rn, cast(cast(dates.beg_YYYYMM as varchar(8)) +'01' as date))

Here's the db<>fiddle

SQL查询扩展每个int的每一行。在COL_A和COL_B之间的范围内

3 个答案: