使用SQL将日期范围拆分为多行

Question

我有一张表格：

startdate                 enddate                   other_columns
1956-05-06 00:00:00.000   1960-04-05 00:00:00.000   myvalues

我需要一个查询，能够将结果返回为：

startdate                 enddate                   other_columns
1956-05-06 00:00:00.000   1956-12-31 00:00:00.000   myvalues
1957-01-01 00:00:00.000   1957-12-31 00:00:00.000   myvalues
1958-01-01 00:00:00.000   1958-12-31 00:00:00.000   myvalues
1959-01-01 00:00:00.000   1959-12-31 00:00:00.000   myvalues
1960-01-01 00:00:00.000   1960-04-05 00:00:00.000   myvalues

基本上是将行分解为年度结果的查询。我需要保留开始和结束日期。

- everydaylearn

---

https://technet.microsoft.com/en-us/library/ms177410%28v=sql.105%29.aspx - Marc B

创建一个日历表（可以是真实的或者是一个计数器），并将其与您的数据进行连接。 - James Z

Answer 1

CREATE TABLE #InputTABLE
(
startdate DATETIME,
enddate DATETIME,
other_columns varchar(20) 
)

INSERT INTO #InputTABLE VALUES('1956-05-06','1960-04-05','myvalues');

SELECT * FROM #InputTABLE

输出：

    startdate                 enddate                   other_columns
    1956-05-06 00:00:00.000   1960-04-05 00:00:00.000   myvalues

查询：

CREATE TABLE #OutputTABLE
(
startdate DATETIME,
enddate DATETIME,
other_columns varchar(20) 
)

DECLARE @cnt int
DECLARE @startDate datetime
DECLARE @endDate datetime
DECLARE @incr int
DECLARE @tempDate datetime 

SET @startDate=(Select startdate from #InputTABLE)
SET @endDate=(Select enddate from #InputTABLE)
SET @cnt=DATEDIFF(yy,@startDate,@endDate)
SET @incr=0

SET @tempDate=DATEADD(yy,@incr,Cast(@startDate As datetime))

WHILE @cnt>=0
BEGIN

   IF @cnt = 0 
      BEGIN
         INSERT INTO #OutputTABLE VALUES(@tempDate,@endDate,'myvalues');
      END
   ELSE
      BEGIN
         insert into #OutputTABLE values(@tempDate,DATEADD(yy, DATEDIFF(yy,0,@tempDate)+1, -1),'myvalues');
      END
   SET @tempDate=DATEADD(yy,@incr+1,DATEADD(yy,DATEDIFF(yy,0,@startDate),0))

   SET @cnt=@cnt-1
   SET @incr=@incr+1

END

Result : SELECT * FROM #OutputTABLE;

startdate                 enddate                   other_columns
1956-05-06 00:00:00.000   1956-12-31 00:00:00.000   myvalues
1957-01-01 00:00:00.000   1957-12-31 00:00:00.000   myvalues
1958-01-01 00:00:00.000   1958-12-31 00:00:00.000   myvalues
1959-01-01 00:00:00.000   1959-12-31 00:00:00.000   myvalues
1960-01-01 00:00:00.000   1960-04-05 00:00:00.000   myvalues

- Khan Abdulrehman

Answer 2

查询非常简单。

SELECT CASE WHEN yrStart<it.startdate THEN it.startdate ELSE yrStart END AS startdate,
       CASE WHEN yrEnd>it.enddate THEN it.enddate ELSE yrEnd END AS enddate,
       other_columns
FROM #InputTABLE it
CROSS APPLY
    (SELECT datefromparts(yr, 1, 1) yrStart, datefromparts(yr, 12, 31) yrEnd
     FROM dbo.yearTable 
     WHERE yr >= datepart(year, it.startdate) AND yr <= datepart(year, it.enddate)
    )years;

你只需要一个包含数字1到9999的年份表（也称为计数表）。这个表中不应该有超出这个范围以外的数字，否则会遇到一些糟糕的转换错误。

- Antonín Lejsek