SQL自我加入条件

Question

我有一张表，列出了我希望一起加入新列的日期列表。我粘贴了以下的例子：

Date 
    03/03/2014 
    03/03/2014 
    03/03/2014 
    04/03/2014 
    04/03/2014 
    04/03/2014 
    04/03/2014 

这是第一个表，但是我想自己加入它，所以它看起来是这样的：

Index_Date Date 
    03/03/2014 03/03/2014 
    03/03/2014 03/03/2014 
    03/03/2014 03/03/2014 
    04/03/2014 03/03/2014 
    04/03/2014 03/03/2014 
    04/03/2014 03/03/2014 
    04/03/2014 04/03/2014 
    04/03/2014 04/03/2014 
    04/03/2014 04/03/2014 
    04/03/2014 04/03/2014 

这仅仅是数据的例子，但希望能够做到这一点的任何帮助！如果您需要更进一步，请告诉我。

谢谢，山姆

下面是一些测试代码，我已经放在一起：

CREATE TABLE #DATES (Date VARCHAR (8)) 

    INSERT INTO #DATES VALUES ('20140303') 
    INSERT INTO #DATES VALUES ('20140303') 
    INSERT INTO #DATES VALUES ('20140303') 
    INSERT INTO #DATES VALUES ('20140304') 
    INSERT INTO #DATES VALUES ('20140304') 
    INSERT INTO #DATES VALUES ('20140304') 
    INSERT INTO #DATES VALUES ('20140304') 

    SELECT 
     T1.Date AS T1Date 
,T2.Date AS T2Date 
    FROM 
#DATES AS T1 
     INNER JOIN #DATES AS T2 
     ON T1.Date = T2.Date 

最终的输出应该是如上图所示的10行。

Answer 1

select 
    dd.Date as T1Date, 
    d.Date as T2Date 
from 
     (select distinct Date from Dates) as dd 
    left join Dates as d on d.Date <= dd.Date 

见http://sqlfiddle.com/#!3/4136c/6

Answer 2

这里是你如何加入一个表与自身

SELECT T1.Date as T1Date, T2.Date as T2Date 
    FROM FooBar T1 
    INNER JOIN FooBar T2 ON T1.Date = T2.Date 

更新根据您的信息，你需要一个工会，而不是自联接：

DECLARE @firstDate DATETIME 
DECLARE @secondDate DATETIME 
SET @firstDate = '2014-03-03' 
SET @secondDate = '2014-03-04' 

SELECT @firstDate as Index_Date, Date FROM @Dates 
     WHERE Date <= @firstDate 
UNION 
SELECT @secondDate as Index_date, Date FROM @Dates 
     WHERE Date <= @secondDate 

两个日期参数可以很容易地如果需要从另一个表中加载。

这也应该也给你你想要什么不上联：

SELECT ID.Index_Date, D.Date 
    FROM IndexDateTable ID 
    INNER JOIN Dates D ON D.Date <= ID.Index_Date