Question

我正在使用带有C＃的ASP.NET开发一个简单的建议基于Web的应用程序。除了一件事，它运作良好。我有以下数据库设计：

表 SafetySuggestionsLog

ID, Title, Description, Username, DateSubmitted, TypeID, OtherTypes

表 SafetySuggestionsType

ID, Type

用户可以填写表格并提交。我可以将用户名，标题，描述和提交的日期插入到数据库中。但我必须插入类型，它是数据库中的一种类型或新的类型。我正在努力解决这个问题，我不知道是谁解决了这个问题。 你能帮我解决这个问题吗？如何将type的值插入数据库？

ASP.NET代码：

<div ID="contactform">
  <ol>
    <li>
      <label for="subject">Type</label>
      <asp:DropDownList ID="DropDownList" runat="server"
       DataSourceID="SqlDataSource1" Width="155px" Font-Bold="True"
       ForeColor="#006666" AppendDataBoundItems="false" DataTextField="Type"
       DataValueField="ID" AutoPostBack="true"
       OnDataBound="DropDownList_DataBound"/>
      <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
       ConnectionString="<%$ ConnectionStrings:testConnectionString %>" 
       SelectCommand="SELECT * FROM [SafetySuggestionsType]"/>
      <asp:TextBox ID="TextBox1" runat="server" CssClass="text"/><br />
      <asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server" 
       ControlToValidate="dropdownlist"
       ErrorMessage="Please select a type ... or choose Others"/>
      <asp:RequiredFieldValidator ID="RequiredFieldValidator4" runat="server" 
       ControlToValidate="TextBox1" 
       ErrorMessage="Please enter a type for your suggestion"/>
    </li>
    <li>
      <label for="subject">Subject</label>
      <asp:TextBox ID="txtSubject" runat="server" CssClass="text"/><br />
      <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" 
       ControlToValidate="txtSubject" 
       ErrorMessage="Please enter a subject/title for your suggestion"/>
    </li>
    <%--The following hidden field is for inserting the date--%>
    <li>
      <asp:TextBox ID="dateSubmitted" runat="server" CssClass="text"
       Visible="false"/><br />
    </li>
    <li>
      <label for="message">Your Suggestion</label>
      <asp:TextBox ID="txtSuggestion" runat="server" cols="50"
       CssClass="textarea" rows="6" TextMode="MultiLine"/><br />
      <asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" 
       ControlToValidate="txtSuggestion"
       ErrorMessage="Please enter your suggestion"/>
    </li>
    <li class="buttons">
      <asp:ImageButton ID="imageField" runat="server"
       ImageURL="images/Send.gif" OnClick="btnSubmit_Click" />
      <%--<input type="image" name="imageField" id="imageField"
       src="images/Send.gif" />--%>
    </li>
  </ol>
</div>

代码隐藏：

protected void btnSubmit_Click(object sender, ImageClickEventArgs e)
{
    SmtpClient sc = new SmtpClient("MAIL.Aramco.com");
    StringBuilder sb = new StringBuilder();
    MailMessage msg = null;

    sb.Append("Message from: " + Service.User.Name + "\n");
    sb.Append("Email: " + Service.User.GetProperty("EMP_BINTERMAIL") + "\n");
    sb.Append("Type: ");
    sb.Append((DropDownList.SelectedItem.Text.Equals("Others")
        ? TextBox1.Text : DropDownList.SelectedItem.Text) + "\n");
    sb.Append("Title: " + txtSubject.Text + "\n");
    sb.Append("Suggestion   : " + txtSuggestion.Text + "\n");

    try
    {
        msg = new MailMessage(Service.User.GetProperty("EMP_BINTERMAIL"),
            "JOHN.ARNESON@ARAMCO.COM", "PSSP: New Safety Suggestion Box",
            sb.ToString());
        sc.Send(msg);
        MultiView1.SetActiveView(ViewConfirm);
    }
    catch (Exception ex)
    {
        throw ex;
        //Response.Write("Something bad happened!");
    }
    finally
    {
        if (msg != null)
        {
            msg.Dispose();
        }
    }

    //For storing the suggestions in the database
    string connString = "Data Source=localhost\\sqlexpress;"
        + "Initial Catalog=psspdbTest;Integrated Security=True";
    string insertCommand = "INSERT INTO SafetySuggestionsLog "
        + "(Title, DateSubmitted, Description, Username) values "
        + "(@Title, @DateSubmitted, @Description, @Username)";
    string username = Service.User.ID;
    using (SqlConnection conn = new SqlConnection(connString))
    {
        conn.Open();
        using (SqlCommand cmd = new SqlCommand(insertCommand, conn))
        {
            cmd.Parameters.Clear(); 
            cmd.Parameters.AddWithValue("@Title", txtSubject.Text);
            cmd.Parameters.AddWithValue("@DateSubmitted",
                DateTime.Now.ToString());
            cmd.Parameters.AddWithValue("@Description", txtSuggestion.Text);
            cmd.Parameters.AddWithValue("@Username", username);
            cmd.ExecuteNonQuery();
        }
    }
}

更新

我修改了用于存储建议信息的代码：

//For stroing the suggestions in the database
        string connString = "Data Source=localhost\\sqlexpress;Initial Catalog=psspdbTest;Integrated Security=True";
        //string insertCommand = "INSERT INTO SafetySuggestionsLog (Title, DateSubmitted, Description, Username) values(@Title, @DateSubmitted, @Description, @Username)";
        string insertCommand = @"insert into SafetySuggestionsLog
                                  ( Title, Description, Username, DateSubmitted, TypeID, OtherTypes ) values
                                  ( @Title, @Description, @Username, @DateSubmitted,
                                    ( select ID from SafetySuggestionsType where Type = @Type ), '?' )";
        string username = Service.User.ID;
        using (SqlConnection conn = new SqlConnection(connString))
        {
            conn.Open();
            using (SqlCommand cmd = new SqlCommand(insertCommand, conn))
            {
                cmd.Parameters.Clear(); 
                cmd.Parameters.AddWithValue("@Title", txtSubject.Text);
                cmd.Parameters.AddWithValue("@DateSubmitted", DateTime.Now.ToString());
                cmd.Parameters.AddWithValue("@Description", txtSuggestion.Text);
                cmd.Parameters.AddWithValue("@Username", username);
                cmd.Parameters.AddWithValue("@Type", DropDownList.SelectedValue);
                cmd.ExecuteNonQuery();
            }
        }

我仍然无法从下拉列表中存储所选类型。即使我选择了其中一个预定义类型，我在数据总线的othertype列下得到（？），在Type列下得到NULL。为什么？

Answer 1

存储过程可以优雅地处理所涉及的步骤。

if not exists ( select 42 from SafetySuggestionsType where Type = @Type )
  insert into SafetySuggestionsType ( Type ) values ( @Type )

insert into SafetySuggestionsLog
  ( Title, Description, Username, DateSubmitted, TypeID, OtherTypes ) values
  ( @Title, @Description, @Username, @DateSubmitted,
    ( select TypeId from SafetySuggestionsType where Type = @Type ), '?' )

Answer 2

您可以使用SqlDbType指定参数类型，如下所示：

   cmd.Parameters.Add("@Title",SqlDbType.VarChar, 20);
     cmd.Parameters["@Title"].Value = txtSubject.Text;

Answer 3

您可以创建类型列主键，当您在数据库中插入新类型时，将抛出异常。因此，在try块中插入记录。

try{
//Do your insertion, if a duplicate item was found, the insertion will not take place
}
catch{
//Do something is an value was inserted which already existed
}

如何将所选类型的建议插入数据库？

3 个答案: