ms-access - DCount 在 Access 中找不到匹配的记录

Question

我没有得到正确的 DCount 值

表是“课程”：
ID（自动）pk
InstructorID As Integer
Weekof As Date
StudentID As Integer
Status As Byte

我的功能是

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

该函数从即时窗口调用为：

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

以下 select 语句确实返回了正确的记录数（应该是 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

在为条件构建字符串参数时，您需要用井号 ( #) 分隔日期值。此外，为了安全起见，它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