在将记录添加到数据库之前检查记录是不是存在

Posted 2023-04-19

【中文标题】在将记录添加到数据库之前检查记录是不是存在

【英文标题】：Check if record exists before adding it to the database在将记录添加到数据库之前检查记录是否存在

【发布时间】：2017-09-08 08:49:04

【问题描述】：

VBA 中有没有一种方法可以在添加记录之前检查数据库中是否存在记录？

我试图在变量中捕获选择查询：

sSQL = "select count(*) from OptionRestriction where Feature_ID_1 = 1021 AND OptionValue_1 = 3 AND value = 0 AND Feature_ID_2 = 403 AND OptionValue_2 = 5 and visible = 1"

我在if语句中使用了变量来检查计数是否不是1。如果语句为真，则应添加记录：

            If sSQL <> "1" Then
                conn.Execute "INSERT INTO OptionRestriction (Feature_ID_1, OptionValue_1, value, Feature_ID_2, OptionValue_2, visible) SELECT TOP(1) CF.FeatureID As Feature_ID_1, CF.OptionValue  As OptionValue_1, 0, OV.FeatureID As Feature_ID_2, OV.OptionValue  AS OptionValue_2, 1 From Value as CF Cross Join Value as OV INNER JOIN Feature f on CF.FeatureID = f.ID INNER JOIN Feature f_2 on OV.FeatureID = f_2.ID Where CF.Name = '" & Replace(s_OptionValue_1_s, "'", "''") & "' AND OV.Name = '" & Replace(s_OptionValue_2_s, "'", "''") & "'"
            End If

但是，这在 VBA 中不起作用。有什么想法可以让我完成这项工作吗？

更新

基于Vityata的cmets，我做了如下改动：

我添加了一个函数：

Public Function RestrictionCount() As Long
     RestrictionCount = DCount("Feature_ID_1", "OptionRestriction", "Feature_ID_1 = 1023 AND OptionValue_1 AND value = 0  AND Feature_ID_2 = 403 AND optionValue_2 = 5 AND visible = 1")
End Function

并在我的 if 所在的代码中使用了函数：

Private Sub CommandButton1_Click()

   Dim conn              As New ADODB.Connection
   conn.Open             "<string to connect to DB. Not displayed here due to confidentiality reasons>"


            If RestrictionCount() <> 1 Then
                conn.Execute "INSERT INTO OptionRestriction (Feature_ID_1, OptionValue_1, value, Feature_ID_2, OptionValue_2, visible) SELECT TOP(1) CF.FeatureID As Feature_ID_1, CF.OptionValue  As OptionValue_1, 0, OV.FeatureID As Feature_ID_2, OV.OptionValue  AS OptionValue_2, 1 From Value as CF Cross Join Value as OV INNER JOIN Feature f on CF.FeatureID = f.ID INNER JOIN Feature f_2 on OV.FeatureID = f_2.ID Where CF.Name = '" & Replace(s_OptionValue_1_s, "'", "''") & "' AND OV.Name = '" & Replace(s_OptionValue_2_s, "'", "''") & "'"
            End If

End Sub

现在我收到一个编译错误，指出子或函数未定义，而 DCount 位于另一个函数中。有没有办法解决这个问题？抱歉我的问题（我是 VBA 新手）。

更新

感谢 Vityata 的最后评论，现在可以执行检查。现在的代码如下，包括我用来将数据添加到数据库的循环：

    rs.ActiveConnection = conn
    rs.Open "select * from OptionRestriction where Feature_ID_1 = 1021 AND OptionValue_1 = 3 AND value = 0 AND Feature_ID_2 = 403 AND OptionValue_2 = 5 and visible = 1"

    i = 2
    Do Until IsEmpty(Cells(i, 1))
        s_OptionValue_1_s = ActiveSheet.Cells(i, 1)
        value_s = ActiveSheet.Cells(i, 2)
        s_OptionValue_2_s = ActiveSheet.Cells(i, 3)

        If value_s <> "" Then

            If rs.RecordCount <> 1 Then
                conn.Execute "INSERT INTO OptionRestriction (Feature_ID_1, OptionValue_1, value, Feature_ID_2, OptionValue_2, visible) SELECT TOP(1) CF.FeatureID As Feature_ID_1, CF.OptionValue  As OptionValue_1, 0, OV.FeatureID As Feature_ID_2, OV.OptionValue  AS OptionValue_2, 1 From Value as CF Cross Join Value as OV INNER JOIN Feature f on CF.FeatureID = f.ID INNER JOIN Feature f_2 on OV.FeatureID = f_2.ID Where CF.Name = '" & Replace(s_OptionValue_1_s, "'", "''") & "' AND OV.Name = '" & Replace(s_OptionValue_2_s, "'", "''") & "'"
            End If

            conn.Execute "INSERT INTO OptionRestriction (Feature_ID_1, OptionValue_1, value, Feature_ID_2, OptionValue_2, visible) SELECT TOP(1) CF.FeatureID As Feature_ID_1, CF.OptionValue  As OptionValue_1, '" & Replace(value_s, "'", "''") & "', OV.FeatureID As Feature_ID_2, OV.OptionValue  AS OptionValue_2, 0 From Value as CF Cross Join Value as OV INNER JOIN Feature f on CF.FeatureID = f.ID INNER JOIN Feature f_2 on OV.FeatureID = f_2.ID Where CF.Name = '" & Replace(s_OptionValue_1_s, "'", "''") & "' AND OV.Name = '" & Replace(s_OptionValue_2_s, "'", "''") & "'"
        Else
            conn.Execute "INSERT INTO OptionRestriction (Feature_ID_1, OptionValue_1, value, Feature_ID_2, OptionValue_2, visible) SELECT TOP(1) CF.FeatureID As Feature_ID_1, CF.OptionValue  As OptionValue_1, 1, OV.FeatureID As Feature_ID_2, OV.OptionValue  AS OptionValue_2, 0 From Value as CF Cross Join Value as OV INNER JOIN Feature f on CF.FeatureID = f.ID INNER JOIN Feature f_2 on OV.FeatureID = f_2.ID Where CF.Name = '" & Replace(s_OptionValue_1_s, "'", "''") & "' AND OV.Name = '" & Replace(s_OptionValue_2_s, "'", "''") & "'"
            conn.Execute "INSERT INTO OptionRestriction (Feature_ID_1, OptionValue_1, value, Feature_ID_2, OptionValue_2, visible) SELECT TOP(1) CF.FeatureID As Feature_ID_1, CF.OptionValue  As OptionValue_1, 0, OV.FeatureID As Feature_ID_2, OV.OptionValue  AS OptionValue_2, 1 From Value as CF Cross Join Value as OV INNER JOIN Feature f on CF.FeatureID = f.ID INNER JOIN Feature f_2 on OV.FeatureID = f_2.ID Where CF.Name = '" & Replace(s_OptionValue_1_s, "'", "''") & "' AND OV.Name = '" & Replace(s_OptionValue_2_s, "'", "''") & "'"
        End If

    i = i + 1
    Loop

现在数据库中的结果是：

然而，被选中的行不应该在那里。所以它只需要添加 1021 - 3 - 0 - 403 - 5 - 1 一次。为了实现这一点，我需要在循环中进行哪些更改？

将数据插入数据库的 excel 文件如下所示：

【问题讨论】：

你在用什么rdbms？

我正在使用 SQL 服务器

您应该看看 TRANSACT SQL 中的 MERGE 语句，如果记录存在或不存在，它会为您提供许多选项。

***.com/questions/11017036/…

【参考方案1】：

如果您使用 MS Excel，以下是您可以使用的示例：

Public Sub CheckDataInSQLServer()

    Dim cnLogs              As Object
    Dim rsData              As Object

    On Error GoTo CheckDataInSQLServer_Error

    Set cnLogs = CreateObject("ADODB.Connection")
    Set rsData = CreateObject("ADODB.Recordset")

    cnLogs.Open ConnectionString 'this is a string function

    rsData.ActiveConnection = cnLogs
    rsData.Open "SELECT * FROM A WHERE B = C;"

    If rsData.EOF Then
        debug.print "no values"
    Else    
        debug.print "has values"
    End If    

End Sub

---

在 VBA 中，如果您使用 MS Access，您需要的函数称为 DCount：

您可以使用 DCount 函数来确定指定记录集（域）中的记录数。使用 Visual Basic 中的 DCount 函数、宏、查询表达式或计算控件。例如，您可以在模块中使用 DCount 函数来返回 Orders 表中与特定日期下达的订单相对应的记录数。 MSDN

查看更多如何使用 DCount - DCount with 2 criteria

这是一个如何在函数中构建DCount 并使用它的示例：

Public Function OrdersCount(ByVal strCountry As String, ByVal dteShipDate As Date) As Long
    OrdersCount = DCount("[ShippedDate]", "Orders", _
                  "[ShipCountry] = '" & strCountry & _
                  "' AND [ShippedDate] > #" & dteShipDate & "#")
End Function

If OrdersCount("Bulgaria", Now()) = 0 then
    'Execute the SQL query.
End if

【讨论】：

亲爱的 Vityata。我在主要问题中发布了更新。你能帮我看看如何让它工作吗？

@user2237168 - 首先尝试使用较少的条件。 Feature_ID_1 = 1023 AND OptionValue_1 AND value = 0 应该是 Feature_ID_1 = 1023 AND OptionValue_1 = 5 AND value = 0。然后确保它有效并编写更多条件。

嗯，是的，但我仍然收到错误：尝试编译时未定义子或函数。我做错了什么？

@user2237168 - 您是在 Excel 中还是在 Access 中使用 VBA？在 Access 中，您应该没有问题。

不再需要帮助了。它通过在 SQL 中使用 NOT EXISTS 来解决:)。不过谢谢你的帮助！！