Question

我正在为客户端的MS Access DB添加一些新功能。原始数据库有几个查询。我需要添加的新功能要求我重新使用这些查询并将它们合并到我的VBA和SQL代码中。

例如，我正在基于以前的查询之一生成新查询（通过VBA和SQL）。然后我将结果导出为excel文件。

但是，每当我尝试运行其中一个新查询时，大约需要15分钟才能完成。在此期间，屏幕右下角显示消息，表示＆＃34;运行查询。＆＃34;

这是我正在运行的SQL查询之一。请注意，当只有一个WHERE条件时，它会快速运行。

SELECT
   StudentProgram.fkCohortID AS [Cohort],
   Student.pkStudentID AS [Student ID],
   Student.EmplID AS [Employee ID],
   Student.LastName AS [Last Name],
   Student.FirstName AS [First Name],
   PostBaccActivity.fkSemesterID AS [Semester],
   PostBaccActivity.fkPostBaccID AS [PostBacc],
   PostBaccActivity.fkGradSchoolID AS [GradSchool],
   PostBaccActivity.ProjectTitle AS [ProjectTitle],
   PostBaccActivity.fkFacultyID AS [Faculty], 
   PostBaccActivity.BeginDate AS [BeginDate],
   PostBaccActivity.EndDate AS [EndDate],
   PostBaccActivity.Status AS [Status] 

FROM qryRptJoinAll
WHERE
       qryRptJoinAll.StudentProgram.fkCohortID  BETWEEN 1 AND 12 
    OR qryRptJoinAll.StudentProgram.fkCohortID = 25 
    OR qryRptJoinAll.StudentProgram.fkCohortID = 28 
    OR qryRptJoinAll.StudentProgram.fkCohortID = 49 
    OR qryRptJoinAll.StudentProgram.fkCohortID = 215 
    OR qryRptJoinAll.StudentProgram.fkCohortID = 220  

 GROUP BY StudentProgram.fkCohortID, Student.pkStudentID, Student.EmplID, Student.LastName,
          Student.FirstName, PostBaccActivity.fkSemesterID, PostBaccActivity.fkPostBaccID,
          PostBaccActivity.fkGradSchoolID, PostBaccActivity.ProjectTitle, PostBaccActivity.fkFacultyID,
          PostBaccActivity.BeginDate, PostBaccActivity.EndDate, PostBaccActivity.Status

这是我用来生成其他查询的查询：

SELECT 
   Student.pkStudentID, Student.EmplID, Student.OldID, Student.Inactive,
   Student.InactiveReason, Student.Status, Student.LastName, Student.MarriedName,
   Student.FirstName, Student.MiddleName, Student.DOB, Student.Sex, Student.SSN,
   Student.Email, Student.Race, Student.Ethnicity, Student.EmailSecondary,
   Student.fkSemesterBCStart, Student.fkSemesterGrad, Student.TotalCredits,
   Student.CreditsAttempted, Student.IndexCredits, Student.QualityPoints,
   Student.LocalCredits, Student.TransferCredits, Student.OtherCredits,
   StudentProgram.*, StudentEvent.*, StudentResearch.*, StudentEmployment.*,
   StudentMajor.*, PostBaccActivity.*, StudentPresentation.*, Presentation.*,
   StudentNote.*, SemesterGPA.*, StudentPublication.*, Publication.*, StudentCourse.fkCourseID,
   StudentCourse.fkFacultyID, StudentCourse.fkSemesterID, StudentCourse.Grade, Grade.GradeValue,
   Grade.NoValue, Course.*, RptCumulativeScienceGPA2.ScienceGPACalc, RptStudentControlList.pkStudentControlID
FROM 

    ((((((((PostBaccActivity RIGHT JOIN ((((((StudentProgram RIGHT JOIN 
Student ON StudentProgram.fkStudentID = Student.pkStudentID)
LEFT JOIN Cohort ON StudentProgram.fkCohortID = Cohort.pkCohortID) LEFT JOIN StudentEmployment ON Student.pkStudentID = StudentEmployment.fkStudentID)
LEFT JOIN StudentNote ON Student.pkStudentID = StudentNote.fkStudentID) LEFT JOIN StudentPresentation ON Student.pkStudentID = StudentPresentation.fkStudentID)
LEFT JOIN Presentation ON StudentPresentation.fkPresentationID = Presentation.pkPresentationID) ON PostBaccActivity.fkStudentID = Student.pkStudentID) 
LEFT JOIN RptCumulativeScienceGPA2 ON Student.pkStudentID = RptCumulativeScienceGPA2.fkStudentID) 
LEFT JOIN RptStudentControlList ON Student.pkStudentID = RptStudentControlList.fkControlID)
LEFT JOIN (StudentPublication LEFT JOIN Publication ON StudentPublication.fkPublicationID = Publication.pkPubID) ON Student.pkStudentID = StudentPublication.fkStudentID)
LEFT JOIN StudentResearch ON Student.pkStudentID = StudentResearch.fkStudentID) LEFT JOIN StudentMajor ON Student.pkStudentID = StudentMajor.fkStudentID)
LEFT JOIN StudentEvent ON Student.pkStudentID = StudentEvent.fkStudentID) 
LEFT JOIN (Course RIGHT JOIN (Grade RIGHT JOIN StudentCourse ON Grade.Grade = StudentCourse.Grade) ON Course.pkCourseID = StudentCourse.fkCourseID) ON Student.pkStudentID = StudentCourse.fkStudentID) 
LEFT JOIN SemesterGPA ON Student.pkStudentID = SemesterGPA.fkStudentID;

无论如何，我可以减少他们跑步所需的时间吗？

Answer 1

在不知道确切查询的情况下，只能提供通用建议：

将索引添加到表中的相关字段，这取决于查询
如果重复相同的查询，请缓存结果并重复使用
可以通过预过滤和缓存来优化大型表的连接
如果可能，实现异步查询，这些查询可以在后台运行时返回部分结果;这可以给出更快响应的错觉

Answer 2

由于您没有使用任何聚合函数，因此请删除GROUP BY子句。
确保StudentProgram.fkCohortID

但我的猜测是实际复杂性在qryRptJoinAll，因此您也必须向我们展示此查询。

从另一个查询生成的访问查询需要很长时间才能运行

2 个答案: