我该如何修复此代码 [英] How do I fix this code

问题描述

使用System; 
使用System.Collections.Generic; 
使用System.Linq; 
使用System.Web; 
使用System.Web.UI; 
使用System.Web.UI.WebControls; 
使用System.Configuration; 
使用System.Data.SqlClient; 
 
 namespace WebApplication1.Resource_Type 
 {
 public partial class编辑：System.Web.UI.Page 
 {
 int id = 0; 
 SqlConnection conn = null; 
 SqlCommand cmd = null; 
 string connectionString = null; 
 
 
 protected void Page_Load（object sender，EventArgs e）
 {
 if（！IsPostBack）
 {
 SqlDataReader dr = null; 
 
 connectionString = ConfigurationManager.ConnectionStrings [FacilityCS]。ConnectionString; 
 
 conn = new SqlConnection（connectionString）; 
 
 string sql =SELECT * from ResourceType; 
 
尝试
 {
 
 cmd = new SqlCommand（sql，conn）; 
 
 conn.Open（）; 
 
 dr = cmd.ExecuteReader（）; 
 
 
} 
 
 catch（例外情况）
 {
 lblOutput.Text =错误消息：+ ex.Message; 
} 
 
最后
 {
 if（conn！= null）
 conn.Close（）; 
} 
 
 if（Request.Params [Id]！= null）
 {
 id = Convert.ToInt32（Request.Params [Id]] ）; 
 
 sql =SELECT * from ResourceType WHERE id = @ Id; 
 
尝试
 {
 cmd = new SqlCommand（sql，conn）; 
 
 cmd.Parameters.AddWithValue（@ Id，id）; 
 
 conn.Open（）; 
 
 dr = cmd.ExecuteReader（）; 
 
 dr.Read（）; 
 
 tbType.Text = dr [Type]。ToString（）; 
 tbDesc.Text = dr [Description]。ToString（）; 
 
 
} 
 
 catch（例外情况）
 {
 lblOutput.Text =错误消息：+ ex.Message; 
} 
 
最后
 {
 if（conn！= null）
 conn.Close（）; 
} 
 
} 
 
其他
 {
 lblOutput.Text =错误。无法从数据库中检索ID。 ; 
} 
} 
} 
 
 protected void btnSubmit_Click（object sender，EventArgs e）
 {
 connectionString = ConfigurationManager.ConnectionStrings [FacilityCS ] .ConnectionString; 
 conn = new SqlConnection（connectionString）; 
 
 string sql =UPDATE ResourceType SET Type = @ Type，Description = @ Description; 
 sql + =WHERE Id = @ Id; 
 
尝试
 {
 cmd = new SqlCommand（sql，conn）; 
 
 cmd.Parameters.AddWithValue（@ Type，tbType.Text）; 
 cmd.Parameters.AddWithValue（@ Description，tbDesc.Text）; 
 
 conn.Open（）; 
 
 int rows = cmd.ExecuteNonQuery（）; 
 
 if（rows> 0）
 {
 lblOutput.Text =记录更新成功; 
} 
} 
 
 catch（例外情况）
 {
 lblOutput.Text =错误消息：+ ex.Message; 
} 
 
最后
 {
 if（conn！= null）
 conn.Close（）; 
} 
} 
} 
} 

这是我的代码。基本上这是编辑数据库的数据，但是当我点击按钮时，错误给了我

Quote：

错误消息：必须声明标量变量 @DescriptionWHERE。

解决方案

在where之前添加一个空格：

 < span class =code-keyword> string  sql =   UPDATE ResourceType SET Type = @ Type，Description = @描述; 
 sql + =   WHERE Id = @ Id; 

你忘了在 WHERE 之前放一个空格。

  string  sql =   UPDATE ResourceType SET Type = @ Type，Description = @ Description ; 
 sql + =   WHERE Id = @ Id; 

它应该是 -

  string  sql =   UPDATE ResourceType SET Type = @ Type，Description = @ Description; 
 sql + =   WHERE Id = @ Id; 

希望，它有帮助:)



更新

您已经忘记在 btnSubmit_Click 中为参数@Id提供值。

 cmd .Parameters.AddWithValue（  @ Type，tbType.Text）; 
 cmd.Parameters.AddWithValue（  @ Description，tbDesc.Text）; 
 cmd.Parameters.AddWithValue（  @ Id，Id）;  //   ID是id的值 

你可以这样写;

string sql = @UPDATE ResourceType SET Type = @ Type，Description = @ Description WHERE Id = @ Id;

 cmd.Parameters.AddWithValue（  @ Type，tbType.Text ）; 
 cmd.Parameters.AddWithValue（  @ Description，tbDesc.Text）; 
 cmd.Parameters.AddWithValue（  @ Id，id  ）; 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Configuration;
using System.Data.SqlClient;

namespace WebApplication1.Resource_Type
{
    public partial class Edit : System.Web.UI.Page
    {
        int id = 0;
        SqlConnection conn = null;
        SqlCommand cmd = null;
        string connectionString = null;


        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                SqlDataReader dr = null;

                connectionString = ConfigurationManager.ConnectionStrings["FacilityCS"].ConnectionString;

                conn = new SqlConnection(connectionString);

                string sql = "SELECT * from ResourceType";

                try
                {

                    cmd = new SqlCommand(sql, conn);

                    conn.Open();

                    dr = cmd.ExecuteReader();


                }

                catch (Exception ex)
                {
                    lblOutput.Text = "Error Message: " + ex.Message;
                }

                finally
                {
                    if (conn != null)
                        conn.Close();
                }

                if (Request.Params["Id"] != null)
                {
                    id = Convert.ToInt32(Request.Params["Id"]);

                    sql = "SELECT * from ResourceType WHERE id=@Id";

                    try
                    {
                        cmd = new SqlCommand(sql, conn);

                        cmd.Parameters.AddWithValue("@Id", id);

                        conn.Open();

                        dr = cmd.ExecuteReader();

                        dr.Read();

                        tbType.Text = dr["Type"].ToString();
                        tbDesc.Text = dr["Description"].ToString();


                    }

                    catch (Exception ex)
                    {
                        lblOutput.Text = "Error Message: " + ex.Message;
                    }

                    finally
                    {
                        if (conn != null)
                            conn.Close();
                    }

                }

                else
                {
                    lblOutput.Text = "Error. There is no ID to retrieve from the DB.";
                }
            }
        }

        protected void btnSubmit_Click(object sender, EventArgs e)
        {
            connectionString = ConfigurationManager.ConnectionStrings["FacilityCS"].ConnectionString;
            conn = new SqlConnection(connectionString);

            string sql = "UPDATE ResourceType SET Type=@Type, Description=@Description";
                   sql += "WHERE Id=@Id";

            try 
            {
                cmd = new SqlCommand(sql, conn);

                cmd.Parameters.AddWithValue("@Type", tbType.Text);
                cmd.Parameters.AddWithValue("@Description", tbDesc.Text);

                conn.Open();

                int rows = cmd.ExecuteNonQuery();

                if(rows > 0)
                {
                    lblOutput.Text = "Record updated successfully";
                }
            }

            catch(Exception ex)
            {
                lblOutput.Text = "Error Message: " + ex.Message;
            }

            finally
            {
                if (conn != null)
                    conn.Close();
            }
        }
    }
}

Hi,this is my code. Basically this is so edit a database's data but when i click the button the error gives me this

Quote:

Error Message: Must declare the scalar variable "@DescriptionWHERE".

解决方案

Add a space before "where" :

string sql = "UPDATE ResourceType SET Type=@Type, Description=@Description";
       sql += " WHERE Id=@Id";

You forgot a to put a blank space before WHERE.

string sql = "UPDATE ResourceType SET Type=@Type, Description=@Description";
                   sql += "WHERE Id=@Id";

It should be -

string sql = "UPDATE ResourceType SET Type=@Type, Description=@Description";
                   sql += " WHERE Id=@Id";

Hope, it helps :)

Update
You have aslo forgotten to provide value for parameter @Id in btnSubmit_Click.

cmd.Parameters.AddWithValue("@Type", tbType.Text);
cmd.Parameters.AddWithValue("@Description", tbDesc.Text);
cmd.Parameters.AddWithValue("@Id", Id); //Id is the value for id

you can write this way;
string sql = @"UPDATE ResourceType SET Type=@Type, Description=@Description WHERE Id=@Id";

cmd.Parameters.AddWithValue("@Type", tbType.Text);
                cmd.Parameters.AddWithValue("@Description", tbDesc.Text);
cmd.Parameters.AddWithValue("@Id", id);

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