DCOUNT在Access

Question

，我没有得到正确的价值DCOUNT

表是 “教训” 没有找到符合条件的记录：
ID（自动）PK
InstructorID作为整数
Weekof截止日期
StudentID作为整数
地位字节

我的F油膏是

Public Function NoRecordsFound(ByVal instructorid As Integer, ByVal weekof As Date, studentid As Integer) As Integer 

    Dim strCriteria As String 
    strCriteria = "Lessons.[InstructorID] = " & instructorid & " AND Lessons.[WeekOf] = " & weekof & " AND Lessons.[StudentID] = " & studentid 

    NoRecordsFound = DCount("*", "Lessons", strCriteria) 
End Function 

功能从即时窗口称为：

:Debug.Print(NoRecordsFound(5, DateValue("10/3/2016"), 17043)) 

以下SELECT语句不会返回正确的记录数（应为1）：

SELECT Lessons.[ID], Lessons.[InstructorID], Lessons.[WeekOf], Lessons.[StudentID], Lessons.[Status] 
FROM Lessons 
WHERE (((Lessons.[InstructorID])=5) AND ((Lessons.[WeekOf])=DateValue("10/3/2016")) AND ((Lessons.[StudentID])=17043)); 

有人可以帮助发现我的DCount表达式中的错误吗？

Answer 1

当构建您需要界定与哈希标记（#）的日期值条件，为字符串参数。此外，为了安全起见，应该被格式化为一个明确的yyyy-mm-dd日期字符串：

strCriteria = "Lessons.[InstructorID] = " & instructorid & " " & _ 
     "AND Lessons.[WeekOf] = #" & Format(weekof, "yyyy-mm-dd") & "# " & _ 
     "AND Lessons.[StudentID] = " & studentid