Question

我正在创建一个带有“代码隐藏”的asp.net Web表单，该表单将数据发送到MS Access数据库。

提交表单后，我收到“参数？_1没有默认值”。我已经浏览了大约6个网站，但我找不到足够接近我的解决方案，我可以使用我有限的VB词汇。我对VB或C＃语言不太熟悉（我只使用Java和C ++）。

我是否需要默认值？如果需要，我该如何添加？

这是.aspx.vb代码（错误源自的地方）：

   Imports System.Data.OleDb

Partial Class _Default
    Inherits System.Web.UI.Page

    Protected Sub SciFairSubmit_Click(sender As Object, e As EventArgs) Handles SciFairSubmit.Click
        'form data requests----------------------------------------------------------------------------C:\Users\NCG-PC\Webmastering\TamugSciFair13\WebSite1\Default1.aspx.vb
        Dim strName As String = Request.Form("FirsNtame") 'In paraenthesis may be the item name in the form
        Dim strLasNtame As String = Request.Form("LasNtame")
        Dim strStudentEmail As String = Request.Form("StudentEmail")

        Dim strSchool As String = Request.Form("School")
        Dim numGrade As Integer = Request.Form("Grade") '*Dropdown list
        Dim strTeacher As String = Request.Form("Teacher") 'Teacher's LasNtame name
        Dim strTeacherEmail As String = Request.Form("TeacherEmail")

        Dim strCatagory As String = Request.Form("Catagory") '*Dropdown list
        Dim strExibitTite As String = Request.Form("ExibitTite") 'Note : "Title" by itself is a keyword and cannot be used
        Dim strElectricity As String = Request.Form("Electricity") '*possible boolean for electricity

        'Open Db Connection---------------------------------------------------------------------------------------------------------
        Dim strSQL As String
        Dim dbconn As OleDbConnection = Nothing

        dbconn = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;data source=" & Server.MapPath("\GalvestonScienceFair\App_Data\sf13.mdb"))
        dbconn.Open()

        'SQL actions ----------------------------------------------------------------------------------------------------------
        strSQL = "INSERT INTO Exhibits (FirsNtame, LasNtame, StudentEmail, School, Grade, Teacher, TeacherEmail, Category, ExibitTite, Electricity) values (@FirsNtame, @LasNtame, @StudentEmail, @School, @Grade, @Teacher, @TeacherEmail, @Category, @ExibitTite, @Electricity)"
        Dim objcmd = New OleDbCommand(strSQL, dbconn)

        objcmd.Parameters.Add(New System.Data.OleDb.OleDbParameter("@FirsNtame", strName))
        objcmd.Parameters.Add(New System.Data.OleDb.OleDbParameter("@LasNtame", strLasNtame))
        objcmd.Parameters.Add(New System.Data.OleDb.OleDbParameter("@StudentEmail", strStudentEmail))

        objcmd.Parameters.Add(New System.Data.OleDb.OleDbParameter("@School", strSchool))
        objcmd.Parameters.Add(New System.Data.OleDb.OleDbParameter("@Grade", numGrade))
        objcmd.Parameters.Add(New System.Data.OleDb.OleDbParameter("@Teacher", strTeacher))
        objcmd.Parameters.Add(New System.Data.OleDb.OleDbParameter("@TeacherEmail", strTeacherEmail))

        objcmd.Parameters.Add(New System.Data.OleDb.OleDbParameter("@Category", strCatagory))
        objcmd.Parameters.Add(New System.Data.OleDb.OleDbParameter("@ExibitTite", strExibitTite))
        objcmd.Parameters.Add(New System.Data.OleDb.OleDbParameter("@Electricity", strElectricity))



        objcmd.ExecuteNonQuery()
        'Number of query values and destination fields are not the same.
        'Close DB Connection
        dbconn.Close()
        Response.Write("Thank you for registering!")
    End Sub
End Class

这是.asp页面（我很确定错误不是来自这里）：

<%@ Page Language="VB" MasterPageFile="~/Site.master" AutoEventWireup="false" CodeFile="ScienceFair.aspx.vb" Inherits="_Default" %>

<asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" Runat="Server">


    <style type="text/css">
        .auto-style1 {
            text-align: center;
        }
    </style>


</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" Runat="Server">
    <div id="RuleBreaker">
    <h2 class="auto-style1">Science Fair Registration</h2>
    <p class="auto-style1" >
        First Name:
        <br />
        <asp:TextBox ID="FirsNtame" runat="server" AutoCompleteType="FirstName"></asp:TextBox>
        <br />

<asp:RequiredFieldValidator id="FirsNtameValidator1" runat="server"
  ControlToValidate="FirsNtame"
  ErrorMessage="A first name is required."
  ForeColor="Red">
</asp:RequiredFieldValidator>
        <br />

        Last Name:
        <br />
        <asp:TextBox ID="LasNtame" runat="server" AutoCompleteType="LastName"></asp:TextBox>
        <br />

<asp:RequiredFieldValidator id="LasNtameValidator2" runat="server"
  ControlToValidate="LasNtame"
  ErrorMessage="A last name is required."
  ForeColor="Red">
</asp:RequiredFieldValidator>
        <br />

        Student Email Address:
        <br />
        <asp:TextBox ID="StudentEmail" runat="server" AutoCompleteType="Email"></asp:TextBox>
        <br />

<asp:RequiredFieldValidator id="StudentEmailValidator3" runat="server"
  ControlToValidate="StudentEmail"
  ErrorMessage="A Student Email is required."
  ForeColor="Red">
</asp:RequiredFieldValidator>

         <br />
         <br />
        School:
         <br />
        <asp:TextBox ID="School" runat="server"></asp:TextBox>
        <br />

<asp:RequiredFieldValidator id="SchoolValidator4" runat="server"
  ControlToValidate="School"
  ErrorMessage="Your school name is required."
  ForeColor="Red">
</asp:RequiredFieldValidator>

         <br />
        Grade:
        <br />
            <asp:DropDownList id="Grade" runat="server" Width="86px">
                <asp:ListItem>7</asp:ListItem>
                <asp:ListItem>8</asp:ListItem>
                <asp:ListItem>9</asp:ListItem>
                <asp:ListItem>10</asp:ListItem>
                <asp:ListItem>11</asp:ListItem>
                <asp:ListItem>12</asp:ListItem>
            </asp:DropDownList>
        <br />

<asp:RequiredFieldValidator id="GradeValidator5" runat="server"
  ControlToValidate="Grade"
  ErrorMessage="A grade is required."
  ForeColor="Red">
</asp:RequiredFieldValidator>

        <br />
            Teacher's Last Name (only):<br />
            <asp:TextBox id="Teacher" runat="server" Width="500px"></asp:TextBox>
            <br />

<asp:RequiredFieldValidator id="TeacherValidator6" runat="server"
  ControlToValidate="Teacher"
  ErrorMessage="A teacher last name is required."
  ForeColor="Red">
</asp:RequiredFieldValidator>
        <br />

            Teacher E-mail:<br />&nbsp;<asp:TextBox ID="TeacherEmail" runat="server" 
                Width="500px"></asp:TextBox>
            <br /> 

<asp:RequiredFieldValidator id="TeacherEmailValidator7" runat="server"
  ControlToValidate="TeacherEmail"
  ErrorMessage="A teacher email is required field."
  ForeColor="Red">
</asp:RequiredFieldValidator>
        <br />

            <%-- Teacher Phone Number:<br />&nbsp;<asp:TextBox id="TPhone" runat="server" Width="500px"></asp:TextBox> --%>
            <%-- Might put the above in later --%>
            Catagory :<br />&nbsp;<asp:DropDownList id="Catagory" runat="server" Width="212px">
                <asp:ListItem>Behavorial &amp; Social Sciences</asp:ListItem>
                <asp:ListItem>Biochemistry &amp; Microbiology</asp:ListItem>
                <asp:ListItem>Botany</asp:ListItem>
                <asp:ListItem>Environmental Sciences</asp:ListItem>
                <asp:ListItem>Medicine &amp; Health</asp:ListItem>
                <asp:ListItem>Zoology</asp:ListItem>
                <asp:ListItem>Chemistry</asp:ListItem>
                <asp:ListItem>Computer Science</asp:ListItem>
                <asp:ListItem>Earth &amp; Space Sciences</asp:ListItem>
                <asp:ListItem>Engineering</asp:ListItem>
                <asp:ListItem>Mathematics</asp:ListItem>
                <asp:ListItem>Physics</asp:ListItem>
            </asp:DropDownList>
            <br />

<asp:RequiredFieldValidator id="CatagoryValidator8" runat="server"
  ControlToValidate="Catagory"
  ErrorMessage="A catagory is required."
  ForeColor="Red">
</asp:RequiredFieldValidator>
        <br />

            Exibit Title :<br />&nbsp;<asp:TextBox id="ExibitTite" runat="server" Width="500px"></asp:TextBox>
            <br />

<asp:RequiredFieldValidator id="ExibitTiteValidator9" runat="server"
  ControlToValidate="ExibitTite"
  ErrorMessage="A title is required."
  ForeColor="Red">
</asp:RequiredFieldValidator>
        <br />

            Does your exhibit use electricity?<br />
            <%-- Possible issues here, may need to use 1 & 0 instead--%>
            <asp:DropDownList id="Electricity" runat="server">
                <asp:ListItem Value="Yes">Yes</asp:ListItem>
                <asp:ListItem Value="No">No</asp:ListItem>
            </asp:DropDownList>
        <br />

 <asp:RequiredFieldValidator id="ElectricityValidator10" runat="server"
  ControlToValidate="Electricity"
  ErrorMessage="Does your computer use electricity?"
  ForeColor="Red">
</asp:RequiredFieldValidator>
        <br />

    </p>
        <p class="auto-style1" >
            <asp:Button ID="SciFairSubmit" runat="server" Text="Submit" />
            <br />
            <br />
    </p>
    </div>

</asp:Content>

Answer 1

您的查询应该是：

INSERT INTO Exhibits (FirsNtame, LasNtame, StudentEmail, School, Grade, Teacher, TeacherEmail, Category, ExibitTite, Electricity) values (@FirsNtame, @LasNtame, @StudentEmail, @School, @Grade, @Teacher, @TeacherEmail, @Category, @ExibitTite, @Electricity)

请参阅：access 2007 oledb with parameters example。问号在旧的ADO中使用，而不是在ADO.NET中使用

修改参数值不可能是空的。设置为nothing的参数将被视为缺失。

可能的消息：

Dim strLasNtame As String = if(Request.Form("LasNtame"),"") objcmd.Parameters.Add(New System.Data.OleDb.OleDbParameter("@FirsNtame", if(strName,DBNull.Value))) For Each param As System.Data.OleDb.OleDbParameter In objcmd.Parameters If param.Value Is Nothing Then param.Value = DBNull.Value End If Next

Answer 2

我在尝试传递可能为“null”的字符串参数时遇到了这个问题，使用一些 C# 代码时，解决方案很简单：

  cmd.Parameters.AddWithValue("@TEXTCOL", myString ?? (object)DBNull.Value);

如何在Visual Studio中解决此错误：“参数？_1没有默认值。”？

2 个答案: