DataTable.Load() 抛出错误：表达式中未定义函数“CountWeekDays”

我正在使用 Access 数据库并尝试加载 DataTable 对象，但收到了错误。我的查询在标准访问模块中调用名为“CountWeekDays”的公共函数，当通过 Access 本身运行时，会返回正确的结果。为什么在通过 .NET 应用程序调用它时这不起作用？

 SELECT tbl1.ProjectID, tbl1.EntryDate AS StartDate, tbl2.EntryDate AS EndDate, 
(SELECT (ChecklistDayMax - ChecklistDayMin + 1) AS DaysAlotted FROM milestone_def WHERE MilestoneDefID = [@milestoneID]) AS DaysAlotted, 
(SELECT ProjectPriority FROM project_master WHERE ProjectID = tbl1.ProjectID) AS Priority,    
 IIF(Priority = 1, (SELECT BonusDaysFH FROM milestone_def WHERE MilestoneDefID = [@milestoneID]), 
 IIF(Priority = 2, (SELECT BonusDaysFM FROM milestone_def WHERE MilestoneDefID = [@milestoneID]), 
 IIF(Priority = 3, (SELECT BonusDaysFL FROM milestone_def WHERE MilestoneDefID = [@milestoneID])))) AS BonusDaysAllotted, 
 CountWeekDays(tbl1.EntryDate, tbl2.EntryDate) AS DaysRequired
 FROM checklist_entries AS tbl1 
 INNER JOIN checklist_entries AS tbl2 ON tbl1.ProjectID = tbl2.ProjectID
 WHERE tbl1.ChecklistDay = (SELECT ChecklistDayMin FROM milestone_def WHERE MilestoneDefID = [@milestoneID])
 AND tbl2.ChecklistDay = (SELECT ChecklistDayMax FROM milestone_def WHERE MileStoneDefID = [@milestoneID]);

仅当查询在 Access 本身内部运行时，才能在 Access 查询中使用用户定义的 VBA 函数。如果您将从 .NET 应用程序中运行查询，则查询将必须仅返回开始/结束日期，并且您的 .NET 代码将必须计算它们之间的工作日数。