c# - 错误 : Object must implement IConvertible

Question

当出现以下错误时，我试图将列表框项和每个列表框项的文本框值插入数据库。

如果我只尝试插入列表框项目，我会成功，但是当我尝试插入文本框值时，我会收到此错误。你能告诉我我做错了什么吗？

Error Message: Object must implement IConvertible.Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.Exception Details: System.InvalidCastException: Object must implement IConvertible.Source Error:Line 60: Line 61:             Line 62:             cmd.ExecuteNonQuery();Line 63: Line 64: 

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c# CODE

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Collections.Specialized;
using System.Text;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Data.SqlClient;
using System.Web.UI.HtmlControls;

public partial class test1 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    private string GetConnectionString()
    {

        return System.Configuration.ConfigurationManager.ConnectionStrings["RM_Jan2011ConnectionString"].ConnectionString;

    }

    private void InsertRecords(StringCollection sc)
    {

        SqlConnection conn = new SqlConnection(GetConnectionString());

        StringBuilder sb = new StringBuilder(string.Empty);


        foreach (string item in sc)
        {
            const string sqlStatement = "INSERT INTO FileID(File_Code, Dept_Code) VALUES(@File_Code, @Dept_Code)";

            sb.AppendFormat("{0}('{1}'); ", sqlStatement, item);

        }

        try
        {
            conn.Open();

            SqlCommand cmd = new SqlCommand(sb.ToString(), conn);



           cmd.Parameters.Add("@File_Code", SqlDbType.VarChar);
        cmd.Parameters["@File_Code"].Value = ListBox2.Items;


        cmd.Parameters.Add("@Dept_Code", SqlDbType.VarChar);
        cmd.Parameters["@Dept_Code"].Value = DropDownList1.Text;



            cmd.ExecuteNonQuery();


            Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "Script", "alert ('Records Successfuly Saved!');", true);
        }


        catch (System.Data.SqlClient.SqlException ex)
        {
            string msg = "Insert Error:";

            msg += ex.Message;

            throw new Exception(msg);
        }
        finally
        {
            conn.Close();
        }
    }


    protected void Button4_Click(object sender, EventArgs e)
    {

        int myint = Convert.ToInt32(TextBox1.Text) + 1;

        for (int i = 1; i < myint; i++)
        {
            ListBox2.Items.Add(DropDownList1.SelectedItem.ToString() + i.ToString());

        }
    }

    protected void Button1_Click(object sender, EventArgs e)
    {

        StringCollection sc = new StringCollection();

        foreach (ListItem item in ListBox2.Items)
        {
            {
                sc.Add(item.Text);
                sc.Add(DropDownList1.Text);
            }
        }
        InsertRecords(sc);
    }

---

我想将列表框的所有值添加到数据库中。

其次，即使我尝试使用 .

选定项

然后我得到以下错误。

Insert Error: Incorrect syntax near 'CPD1'. Incorrect syntax near 'CPD'. Incorrect syntax near 'CPD2'. Incorrect syntax near 'CPD'. Incorrect syntax near 'CPD3'. Incorrect syntax near 'CPD'.

知道我哪里出错了吗？

Answer 1

如果您的列表框只包含您需要更改以下行的字符串项

cmd.Parameters["@File_Code"].Value = ListBox2.Items

到

cmd.Parameters["@File_Code"].Value = ListBox2.SelectedItem

如果项目是复杂的对象，在末尾添加 .ToString()

UPD:如果你想添加所有 ListBox 项目，你需要循环遍历其项目集合并为每个项目执行插入查询，如下所示:

foreach(string item in ListBox2.Items)
{
    SqlCommand cmd = new SqlCommand(sqlStatement, conn);       
    cmd.Parameters.Add("@File_Code", SqlDbType.VarChar);    
    cmd.Parameters["@File_Code"].Value = item;    
    cmd.Parameters.Add("@Dept_Code", SqlDbType.VarChar);    
    cmd.Parameters["@Dept_Code"].Value = DropDownList1.Text;        
    cmd.ExecuteNonQuery();
}