Question

我需要在JOIN-ed表上执行JOIN，我不知道如何完成它。希望下面的查询能说明我正在尝试做什么：获取国家名称，每个国家的领导者以及每个领导者的家乡。

我认为此查询的问题是在与President.HomeTown_Id的第二次联接中使用JOIN-ed表“President”。我不知道还有什么可以尝试。

SELECT 
  Countries.Name AS Country, 
  President.Name AS Leader,
  PresidentHomeTown.Name AS LeaderHomeTown
FROM Countries
  LEFT OUTER JOIN PoliticalFigures AS President ON Countries.President_Id = President.Id
  LEFT OUTER JOIN Cities AS PresidentHomeTown ON President.HomeTown_Id = PresidentHomeTown.Id

在VS中，我收到错误，“多部分标识符”President.Id“无法绑定。”

表和字段的名称是虚构的，但我需要解决相同的问题。我更改名称以使事情更清楚;希望这对更多人有用。

- 更新 -

也许原始代码有帮助：

SELECT 
    CaseComparisons.Directory AS CaseComparisonDir, 
    BaselineResult.Directory AS BaselineResultDir, 
    ComparisonResult.Directory AS ComparisonResultDir,
    Setup.FullSvnLink AS SvnLink,
    BaselineVersion.FullFilePath AS BaselineExecutableDir
FROM CaseComparisons 
    LEFT OUTER JOIN Results AS BaselineResult ON CaseComparisons.BaselineResult_Id = Baseline.Id 
    LEFT OUTER JOIN Results AS ComparisonResult ON CaseComparisons.ComparisonResult_Id = Comparison.Id
    LEFT OUTER JOIN Setups AS Setup ON Baseline.Setup_Id = Setups.Id
    LEFT OUTER JOIN BuildVersions AS BaselineVersion ON BaselineResult.Version_Id = BuildVersions.Id
WHERE 
    CaseComparisons.Status = 'Queued' OR 
    Baseline.Status = 'Queued' OR 
    Comparison.Status = 'Queued'

运行查询时出现的错误：

The multi-part identifier "Baseline.Id" could not be bound.
The multi-part identifier "Comparison.Id" could not be bound.
The multi-part identifier "Baseline.Setup_Id" could not be bound.
The multi-part identifier "Setups.Id" could not be bound.
The multi-part identifier "BuildVersions.Id" could not be bound.
The multi-part identifier "Baseline.Status" could not be bound.

Answer 1

您指定的别名（例如Results AS ComparisonResult中）和您尝试使用的别名（例如Comparison.Id）之间存在不匹配。所以，改变这个：

    LEFT OUTER JOIN Results AS ComparisonResult
                 ON CaseComparisons.ComparisonResult_Id = Comparison.Id

要么：

    LEFT OUTER JOIN Results AS ComparisonResult
                 ON CaseComparisons.ComparisonResult_Id = ComparisonResult.Id

或者这个：

    LEFT OUTER JOIN Results AS Comparison
                 ON CaseComparisons.ComparisonResult_Id = Comparison.Id

（同样适用于所有其他联接）。

Answer 2

您在总统表中没有Id列。仔细检查一下。

Answer 3

试试这个，你的名字不同：

SELECT 
    CaseComparisons.Directory AS CaseComparisonDir, 
    BaselineResult.Directory AS BaselineResultDir, 
    ComparisonResult.Directory AS ComparisonResultDir,
    Setup.FullSvnLink AS SvnLink,
    BaselineVersion.FullFilePath AS BaselineExecutableDir
FROM CaseComparisons 
    LEFT OUTER JOIN Results AS BaselineResult ON CaseComparisons.BaselineResult_Id = BaselineResult.Id 
    LEFT OUTER JOIN Results AS ComparisonResult ON CaseComparisons.ComparisonResult_Id = ComparisonResult.Id
    LEFT OUTER JOIN Setups AS Setup ON BaselineResult.Setup_Id = Setup.Id
    LEFT OUTER JOIN BuildVersions AS BaselineVersion ON BaselineResult.Version_Id = BaselineVersion.Id
WHERE 
    CaseComparisons.Status = 'Queued' OR 
    BaselineResult.Status = 'Queued' OR 
    ComparisonResult.Status = 'Queued'

如何在JOIN-ed表上执行JOIN？

3 个答案: