如何通过ComboBox从Visual向Access数据库输入多个ComboBox值

Question

使用我正在运行的当前代码，不会发生错误，但不会将任何数据添加到Microsoft中。只有在代码中包含了2个或更少的ComboBoxes时，它才会将数据上载到DB。这让我很困惑。我已经尝试过ComboBox1.SelectedItem.ToString、ComboBox1.SelectedItem.Text和ComboBox1。文本和类似的问题都会出现。有什么想法吗？

Imports System.Data.OleDb

Public DefineDataFile As String
Dim provider As String
Dim dataFile As String
Dim connString As String
Dim myConnection As OleDbConnection = New OleDbConnection


    provider = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source="
    dataFile = "XXXXXXXXXXXXX.mdb"
    connString = provider & dataFile
    myConnection.ConnectionString = connString
    myConnection.Open()

    Dim str As String
    str = "INSERT INTO [Panels/Equipment] ([Panel/Equipment Name], [Machine Name], [Panel/Equipment #], [Type], [Functional Location], [Facility], [Category], [Lifetime Cost Savings], [Hours Per Day], [Days Per Week], [Weeks Per Year], [Description], [Environmental Condition], [Environmental Option], [Environmental Finding], [Heating/Cooling Condition], [Heating/Cooling Option], [Heating/Cooling Finding], [Wiring Condition], [Wiring Option], [Wiring Finding], [Machines ID])"
    str += "SELECT ?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,[Machines].[Machines ID]"
    str += "FROM [Machines] WHERE [Machines].[Machine Name] = ? "

    Dim cmd As OleDbCommand = New OleDbCommand(str, myConnection)
    cmd.Parameters.Add(New OleDbParameter("Panel/Equipment Name", CType(TextBox_Name.Text, String)))
    cmd.Parameters.Add(New OleDbParameter("Machine Name", CType(TextBox_Machine.Text, String)))
    cmd.Parameters.Add(New OleDbParameter("Panel/Equipment #", CType(TextBox_PENum.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Type", CType(ComboBox_Type.SelectedItem.Text, String)))
    cmd.Parameters.Add(New OleDbParameter("Functional Location", CType(TextBox_FunctionalLocation.Text, String)))
    cmd.Parameters.Add(New OleDbParameter("Facility", CType(TextBox_Facility.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Category", CType(ComboBox_Category.SelectedItem.Text, String)))
    cmd.Parameters.Add(New OleDbParameter("Lifetime Cost Savings", CType(TextBox_LifetimeCostSavings.Text, String)))
    cmd.Parameters.Add(New OleDbParameter("Hours Per Day", CType(TextBox_HoursPerDay.Text, String)))
    cmd.Parameters.Add(New OleDbParameter("Days Per Week", CType(TextBox_DaysPerWeek.Text, String)))
    cmd.Parameters.Add(New OleDbParameter("Weeks Per Year", CType(TextBox_WeeksPerYear.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Priority", CType(ComboBox_Priority.SelectedItem.Text, String)))
    cmd.Parameters.Add(New OleDbParameter("Description", CType(TextBox_Description.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Environmental Condition", CType(ComboBox_EC.SelectedItem.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Environmental Option", CType(ComboBox_EO.SelectedItem.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Environmental Finding", CType(ComboBox_EF.SelectedItem.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Heating/Cooling Condition", CType(ComboBox_HCC.SelectedItem.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Heating/Cooling Option", CType(ComboBox_HCO.SelectedItem.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Heating/Cooling Finding", CType(ComboBox_HCF.SelectedItem.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Wiring Condition", CType(ComboBox_WC.SelectedItem.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Wiring Option", CType(ComboBox_WO.SelectedItem.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Wiring Finding", CType(ComboBox_WF.SelectedItem.Text, String)))
 *  cmd.Parameters.Add(New OleDbParameter("Machine ID", CType(ComboBox_Machine.SelectedItem.ToString, String)))
   Try
        cmd.ExecuteNonQuery()
        cmd.Dispose()
        myConnection.Close()
        MsgBox("Panel/Equipment Successfully Added")

    Catch ex As Exception
        MsgBox(ex.Message)
    End Try
    myConnection.Close()

Answer 1

为什么要将文本转换为字符串？在CType(TextBox_Name.Text, String)中，表达式TextBox_Name.Text已经是一个字符串了。简单地写

cmd.Parameters.Add(New OleDbParameter("Panel/Equipment Name", TextBox_Name.Text))

对于其他参数，必须提供与表列中的类型匹配的类型的值。例如，如果Access中的机器ID是数字长(32位)，则编写

cmd.Parameters.Add(New OleDbParameter("Machine ID", _
    CType(ComboBox_Machine.SelectedItem, Integer))) 'Integer in VB is 32-bit

此外，您有21个?，但正在插入23个参数。Priority参数似乎是错误的。因为直接在INSERT中插入Machine ID，所以不应该为它添加一个参数，而应该在where子句中为Machine Name添加一个参数。

SelectedItem属性的ComboBox返回一个Object。对象不包含属性Text。组合框中包含什么样的对象？如果您添加了字符串，那么SelectedItem已经是一个字符串了。例如。

cmd.Parameters.Add(New OleDbParameter("Type", ComboBox_Type.SelectedItem))

此外，我建议您在VB中使用项目选项Strict On，因为这显示了未显示的编码错误。