Question

如果我在所需的日期/时间字段上使用Max（SampleDateTime）或Min（），我的查询返回1值，但如果我省略Max或Min，则不返回任何值。我想要返回所有值，但我似乎无法弄清楚这一点。

我希望生产运行的开始和停止时间之间的所有质量样本。

RunSamples：

Select Max([SampleDateTime]) 
FROM [QualitySamples] AS [GoodSamples] 
WHERE [GoodSamples].[SampleDateTime] >= [ProductionRuns_tbl].[RunStartDate] 
    AND [GoodSamples].[SampleDateTime] <= [ProductionRuns_tbl].[RunEndDate]

ProductionRuns_tbl：
RunStartDate RunEndDate
1/1/2017 12 AM 1/5/17 12 AM
...

QualitySamples Tbl：
ID SampleDateTime
1 1/1/2017 2上午 2 1/1/2017 3上午 ...

这是完整的SQL代码：

SELECT ProductionRuns_tbl.RunName, ProductionRuns_tbl.RunStartDate, 
ProductionRuns_tbl.RunEndDate,
 (Select Max([SampleDateTime]) 
 FROM [QualitySamples] AS [GoodSamples] 
 WHERE [GoodSamples].[SampleDateTime] >= [ProductionRuns_tbl].[RunStartDate] 
 AND [GoodSamples].[SampleDateTime] <= [ProductionRuns_tbl].[RunEndDate])
AS RunSamples
FROM ProductionRuns_tbl
WHERE (((ProductionRuns_tbl.RunName)=[Forms]![Home]![RunName]));

Answer 1

尝试使用连接：

SELECT ProductionRuns_tbl.RunName,
       ProductionRuns_tbl.RunStartDate, 
       ProductionRuns_tbl.RunEndDate,
        GoodSamples.SampleDateTime
FROM QualitySamples GoodSamples INNER JOIN ProductionRuns_tbl ON 
    GoodSamples.SampleDateTime >= ProductionRuns_tbl.RunStartDate AND 
    GoodSamples.SampleDateTime <= ProductionRuns_tbl.RunEndDate
WHERE ProductionRuns_tbl.RunName=[Forms]![Home]![RunName]

Answer 2

不要 WHERE ， MAX 或 MIN 。只需要 SELECT 查询。

Select [SampleDateTime]
FROM [QualitySamples] AS [GoodSamples]

Answer 3

我现在正在冒险发布，因为我必须尝试阅读你想要做的事情（另外，我不知道这是否适用于Access ，但它将在SQL服务器中工作）

由于您需要所有数据，这是您正在寻找的内容吗？

SELECT 
    ProductionRuns_tbl.RunName, 
    ProductionRuns_tbl.RunStartDate, 
    ProductionRuns_tbl.RunEndDate,
    [QualitySamples].[SampleDateTime]
FROM
    ProductionRuns_tbl
LEFT JOIN
    [QualitySamples]
ON
    [QualitySamples].[SampleDateTime] >= [ProductionRuns_tbl].[RunStartDate] 
    AND
    [QualitySamples].[SampleDateTime] <= [ProductionRuns_tbl].[RunEndDate]
WHERE 
    (((ProductionRuns_tbl.RunName)=[Forms]![Home]![RunName]));

这应列出为每个SampleDateTime重复的RunName，Start和End日期。根据您的更具体要求，您可以从那里优化结果。

SQL：在日期范围之间选择

3 个答案: