DLookUp 返回运行时错误 424 - 需要对象答案

【问题标题】：DLookUp returning run-time error 424 - Object RequiredDLookUp 返回运行时错误 424 - 需要对象
【发布时间】：2019-11-26 16:28:51
【问题描述】：

我是 VBA 新手，正在尝试获取我正在编写的宏，以检查是否已经存在与要添加的新记录的日期/班次组合相对应的预先存在的记录。为此，我正在尝试使用 DLookup 搜索数据库，并且仅在 DLookup 返回 Null 时才允许新记录，除非它找到日期和班次都与新数据匹配的记录（我' m 使用复合主键使用这两条数据）。唉，正如标题所说，我不断收到运行时错误 424，当我调试它时它会突出显示

lookTest = Access.DLookup("Shift", "trialTable", "[Date of Production]=#" & shiftDate & "#" & "And [Shift]='" & currentShift & "'")

作为问题线。（“Shift”和“Date of Production”是用作复合键的两列的列标题，“trialTable”是我正在使用的表，“shiftDate”是日期，“currentShift”是字符串）据我所知，我的语法是正确的，所以我不知道此时我哪里出了问题（我敢肯定，这可能是愚蠢而明显的事情）。如果它有帮助，下面是导致该点的其余代码，以防我之前搞砸了一些东西，而计算机直到它到达那条线才意识到它。非常感谢任何帮助，谢谢！

Sub DatabaseUpdate()
' exports data from the active spreadsheet to a table in an Access database
' this procedure must be edited before use
Dim cn As ADODB.Connection, rs As ADODB.Recordset
    ' connect to the Access database
    Set cn = New ADODB.Connection
    cn.Open "Provider=Microsoft.Ace.OLEDB.12.0; " & "Data Source=H:\TestingDatabase.accdb;"
    ' open a recordset
    Set rs = New ADODB.Recordset
    rs.Open "trialTable", cn, adOpenKeyset, adLockOptimistic, adCmdTable
    ' all records on a table
    With rs
        .AddNew 'create a new record

        'Ask the user which shift the report is for.
        Dim currentShift As String
        Dim shiftDate As Date
        Dim shiftCheck As Boolean
        shiftCheck = False

        ' Request and check if the user has entered in a valid shift. If so, continue. If not, inform them and then repeat the request for the shift identity.
        Do While shiftCheck = False
            currentShift = UCase(InputBox("Which shift is this entry for? Please input only A, B, or C. (not case-sensitive)"))
            If currentShift = "A" Or currentShift = "B" Or currentShift = "C" Then
                shiftCheck = True
            Else
                wrongLetterWarning = MsgBox("Sorry, that is not an accepted response (A, B, or C). Please try again.", vbOKOnly)
            End If
        Loop

        ' Request the date the shift occured on. MM/DD/YYYY format is important as the date and shift together form the database's primary key.
        shiftDate = InputBox("On which date did this shift occur? Please use MM/DD/YYYY format.")

        'Check to make sure that there isn't already a pre-existing record for the date/shift combination.
        Dim lookTest As Variant
        lookTest = Access.DLookup("Shift", "trialTable", "[Date of Production]=#" & shiftDate & "#" & "And [Shift]='" & currentShift & "'")

【问题讨论】：

什么是Access？
开启Option Explicit，看看编译时会发生什么。
@GSerg：MS Access @braX：首先它让我将变量 wrongLetterWarning 指定为一个变体，现在它出于某种原因将 Access 标记为一个变量（它不是一个）并说它是未定义的。
当然是未定义的。 MS Access 对象模型中没有Access 这样的东西。虽然有Application，但它确实有DLookUp 作为它的方法。
@Grahammophone 该 VBA 代码是包含在 Excel 项目还是 Access 项目中？ DatabaseUpdate 中的代码注释提到了“excel 电子表格”。

标签： vba ms-access runtime-error dlookup

【解决方案1】：

我在 Excel 中测试了 DLookup，如果数据库是物理打开的，它会找到表。由于您已连接到数据库并已打开记录集，因此请对记录集应用过滤器。

'code to collect data
...
rs.Open "SELECT * FROM trialTable WHERE [Date of Production]=#" & shiftDate & "# And [Shift]='" & currentShift & "'", cn, adOpenKeyset, adLockOptimistic
If rs.EOF And rs.BOF Then
    'code to create record
    ...
Else
    MsgBox "Record already exists."
End If

【讨论】：