SQL自我加入條件

Question

我有一張表，列出了我希望一起加入新列的日期列表。我粘貼了以下的例子：

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

這是第一個表，但是我想自己加入它，所以它看起來是這樣的：

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 

這僅僅是數據的例子，但希望能夠做到這一點的任何幫助！如果您需要更進一步，請告訴我。

謝謝，山姆

下面是一些測試代碼，我已經放在一起：

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 

最終的輸出應該是如上圖所示的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 

見http://sqlfiddle.com/#!3/4136c/6

Answer 2

這裏是你如何加入一個表與自身

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

更新根據您的信息，你需要一個工會，而不是自聯接：

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 

兩個日期參數可以很容易地如果需要從另一個表中加載。

這也應該也給你你想要什麼不上聯：

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