Question

我想提出一个请求，从昨天开始计算第一列的所有结果，并为第二列做同样的事情，但是为期2天。

下面的请求不起作用，因为我想找到一种方法将Where子句与特定列关联。

SELECT
Count(*) as '1 day',
Count(*) as '2 days'
       FROM myTable tbl
       WHERE
       DATEADD(day, 1, MyTimeStampToCompare) >= DATEADD(day, -1, GETDATE()) as '1 day' and 
       DATEADD(day, 1, MyTimeStampToCompare) >= DATEADD(day, -3, GETDATE()) as '2 days'

我正在研究SQL Server 2012。

由于

Answer 1

而不是在where子句中将其修改为CASE函数内的COUNT语句

SELECT COUNT(CASE WHEN DATEADD(day, 1, MyTimeStampToCompare) >= DATEADD(day, -1, GETDATE()) THEN 1
                  ELSE NULL
             END) AS '1 Day'
       ,COUNT(CASE WHEN DATEADD(day, 1, MyTimeStampToCompare) >= DATEADD(day, -2, GETDATE()) THEN 1
                   ELSE NULL
              END) AS '2 Day'
    FROM MyTable
    WHERE MyTimeStampToCompare >= DATEADD(day, -4, GETDATE())

在where子句中，我包括最后4天缩小返回的记录数量，使其更快。

Answer 2

长时间不使用Ms SQL，但是，你似乎需要这样的东西吗？

SELECT
SUM(CASE WHEN DATEADD(day, 1, first_date_col)>= GETDATE() THEN 1 ELSE 0 END) as '1 day',
SUM(CASE WHEN DATEADD(day, 2, secornd_date_col)>= GETDATE() THEN 1 ELSE 0 END) as '2 day',
FROM myTable tbl

（修复！@Vladimir：打算在写入1时使用从开头的总和0，只是忘记更改COUNT：）

Answer 3

你应该确保WHERE子句可以追溯到你想要的最远的计数。

您可以像我这样使用SUM，或像其他答案那样使用COUNT。 COUNT依赖于NULL不被计数，并且可以触发“警告：Null值被聚合消除......”警告。

DECLARE @DateTable TABLE
(
    MyTimeStampToCompare datetime
);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-7);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-1);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-1);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-1);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-1);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-1);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-5);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-3);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-5);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-2);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-2);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-2);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate());
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-3);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-6);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-8);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-9);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()+1);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate()-1);
INSERT INTO @DateTable (MyTimeStampToCompare) VALUES (getdate());

SELECT
    SUM
    (
        CASE
            WHEN MyTimeStampToCompare >= DATEADD(day, -1, FLOOR(CONVERT(float,getdate()))) THEN
                1
            ELSE
                0
        END
    ) AS EverythingSince1DayAgo,
    SUM
    (
        CASE
            WHEN MyTimeStampToCompare >= DATEADD(day, -2, FLOOR(CONVERT(float,getdate()))) THEN
                1
            ELSE
                0
        END
    ) AS EverythingSince2DaysAgo
FROM        @DateTable
-- you said you want everything from 2 days ago; this makes sure times are stripped off of the current date so it's midnight this morning, and then marches back 2 days
-- SQL Server 2008+ has fancier mechanisms for removing the time from a date, but I don't have convenient access to test.
WHERE       MyTimeStampToCompare >= DATEADD(day, -2, FLOOR(CONVERT(float,getdate())));

/*
Original poster's errant code:
SELECT
Count(*) as '1 day',
Count(*) as '2 days'
       FROM myTable tbl
       WHERE
       DATEADD(day, 1, MyTimeStampToCompare) >= DATEADD(day, -1, GETDATE()) as '1 day' and 
       DATEADD(day, 1, MyTimeStampToCompare) >= DATEADD(day, -3, GETDATE()) as '2 days'
*/

SQL请求 - 从不同列中的2个日期获取结果

3 个答案: