Question

- 我想在TIME数据类型上使用SQL - BETWEEN。

我想执行以下查询，但它没有给出正确的结果。在这里，starttime和endtime这两个字段都是smalldatetime的类型，因为我只需要时间比较，而且日期的值不是实际的，只是假的。{/ p>

SELECT 
  count(1) 
FROM 
  t1 INNER JOIN t2
WHERE 
  CAST(t1.StartTime as TIME)  
  BETWEEN CAST(t2.StartTime as TIME) 
  AND CAST(t2.EndTime as TIME)

CAST(t1.StartTime as TIME)  is 08:00:00.0000000 
CAST(t2.StartTime as TIME)  is 07:00:00.0000000 
CAST(t2.StartTime as TIME)  is 12:00:00.0000000

所以，上面的查询应该得到记录计数1（因为8点在7到12之间）。但它返回null。

请告诉我这里有什么问题以及如何纠正。

谢谢

Answer 1

WHERE CAST(t1.StartTime as TIME)  >= CAST(t2.StartTime as TIME) 
AND CAST(t1.StartTime as TIME) <= CAST(t2.EndTime as TIME)

使用此Snytax可使您的查询成为SARGable。 Read Here有关在使用datetime / date / time数据类型时使查询具有可查询性的更多信息。

Answer 2

之间的语法是正确的。您需要指定连接并提供如下on子句：

SELECT count(1) FROM t1 INNER JOIN t2 on t1.col = t2.col
WHERE CAST(t1.StartTime as TIME)  BETWEEN CAST(t2.StartTime as TIME) AND CAST(t2.EndTime as TIME)

Answer 3

我怀疑你的例子是你在t1中在t1的开始和结束时间之间寻找时间，但是这两个表在任何键上都不一定有它们之间的关系。

尝试在该场景中使用连接将无法轻松工作，您必须将M. Ali的解决方案移动到连接谓词而不是where条件。

如果我的假设是正确的并且你只是在t2中寻找符合你们之间标准的t1行，这应该可以让你在没有两个表有关系的情况下进行设置：

DECLARE @sampleTime AS smalldatetime = GETDATE()

CREATE TABLE #t1 (StartTime smalldatetime)
CREATE TABLE #t2 (StartTime smalldatetime, EndTime smalldatetime)

INSERT INTO #t1 (StartTime) VALUES (@sampleTime)
INSERT INTO #t1 (StartTime) VALUES (DATEADD(hh, 6, @sampleTime))

INSERT INTO #t2 (StartTime, EndTime) VALUES (DATEADD(hh, -1, @sampleTime), DATEADD(hh, 3, @sampleTime))

--  you can see only one row in t1 lands between the Start and End in t2 
SELECT  * FROM #t1
WHERE   EXISTS(SELECT * FROM #t2  WHERE CAST(#t1.StartTime AS time) BETWEEN CAST(#t2.StartTime AS time) AND CAST(#t2.EndTime AS time))


--  adding another row to t1 that now lands between the Start and End in t2 and the result
INSERT INTO #t1 (StartTime) VALUES (DATEADD(hh, 1, @sampleTime))

SELECT  * FROM #t1
WHERE   EXISTS(SELECT * FROM #t2  WHERE CAST(#t1.StartTime AS time) BETWEEN CAST(#t2.StartTime AS time) AND CAST(#t2.EndTime AS time))


DROP TABLE #t1, #t2

如何在TIME数据类型上应用SQL'之间'关键字

3 个答案: