Question

我有一个users表，其中包含字段uname，ushortname和pswd以及ucode作为主键。以下UPDATE无效：

protected void Page_Load(object sender, EventArgs e)
    {

        string uname = Request.QueryString["uname"];
        string ucode = Request.QueryString["ucode"];
        if (!string.IsNullOrEmpty(uname))
        {
            SqlCommand cmd = new SqlCommand("select * from users WHERE ucode=@ucode", conn);
            SqlDataAdapter dadapter = new SqlDataAdapter();
            conn.Open();
            txtUserName.ReadOnly = false;
            txtUserShortName.ReadOnly = false;
            txtPassword.ReadOnly = false;
            dadapter.SelectCommand = cmd;
            cmd.Parameters.Add(new SqlParameter("@ucode", ucode));
            SqlDataReader dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                LblUcode.Text = dr["ucode"].ToString();
                txtPassword.Text=dr["pswd"].ToString();
                txtUserShortName.Text = dr["ushortname"].ToString();
                txtUserName.Text = dr["uname"].ToString();
                            }
            dr.Close();
            conn.Close();
        }
    }    
SqlCommand cmd = new SqlCommand("update users Set uname=@Uname,ushortname=@Ushortname,pswd=HASHBYTES('MD5',@Pswd) where ucode=@UCODE", conn);
    cmd.Parameters.AddWithValue("@Uname", txtUserName.Text);
    cmd.Parameters.AddWithValue("@Ushortname", txtUserShortName.Text);
    cmd.Parameters.AddWithValue("@Pswd", txtPassword.Text);
    cmd.Parameters.AddWithValue("@UCODE", LblUcode.Text);
    cmd.ExecuteNonQuery();
    cmd.Dispose();

没有错误，数据根本没有更新。

Answer 1

试试这个： -

using(SqlConnection conn = new SqlConnection(CS))
{
   using (SqlCommand cmd = new SqlCommand("update users Set uname=@Uname,ushortname=@Ushortname,pswd=HASHBYTES('MD5',@Pswd) where ucode=@UCODE ", conn))
  {
    cmd.Parameters.AddWithValue("@Uname", txtUserName.Text);
    cmd.Parameters.AddWithValue("@Ushortname", txtUserShortName.Text);
    cmd.Parameters.AddWithValue("@Pswd", txtPassword.Text);
    cmd.Parameters.AddWithValue("@UCODE", UCODE);
    conn.Open();
    cmd.ExecuteNonQuery();
  }
}

您在Ucode中缺少@。此外，将代码封装在using块检查this中是一种很好的做法。

Answer 2

参见下面编辑的代码： -

if (!PostBack)
{
   string databaseconnectionstring = System.Configuration.ConfigurationManager.ConnectionStrings["ConnectionName"].ConnectionString;
   string sql = "update users Set uname=@Uname,ushortname=@Ushortname,pswd=HASHBYTES('MD5',@Pswd) where ucode=@UCODE";    
   using (SqlConnection conn = new SqlConnection(databaseconnectionstring))
   {
     conn.Open();
     using (SqlCommand cmd= new SqlCommand())
     {
        cmd.CommandText=sql;
        cmd.Connection=databaseconnectionstring;
        cmd.Parameters.AddWithValue("@Uname",txtUserName.Text );
        cmd.Parameters.AddWithValue("@Ushortname",txtUserShortName.Text );
        cmd.Parameters.AddWithValue("@Pswd",txtPassword.Text );
        cmd.Parameters.AddWithValue("@UCODE", UCODE);
        cmd.ExecuteNonQuery();
        conn.Close();
        cmd.Dispose();
     }
  }
}

Answer 3

您需要确保参数名称与它们在sql字符串中的作用完全匹配。

cmd.Parameters.AddWithValue("@UCODE", UCODE);

此外，要么将所有内容包装在using或try / finally中以处理连接。我假设你已经有代码在尝试执行之前打开连接。

Answer 4

protected void Page_Load(object sender, EventArgs e)
        {        
            string bsname = Request.QueryString["bsname"];
            string bscode = Request.QueryString["bscode"];
            if (!string.IsNullOrEmpty(bsname))
            {

               if (string.IsNullOrEmpty(txtBsName.Text))
               {
                 SqlCommand cmd = new SqlCommand("select * from bs WHERE bscode=@bscode", conn);
                 SqlDataAdapter dadapter = new SqlDataAdapter();
                 conn.Open();
                 txtBsName.ReadOnly = false;
                 dadapter.SelectCommand = cmd;
                 cmd.Parameters.Add(new SqlParameter("@bscode", bscode));
                 SqlDataReader dr = cmd.ExecuteReader();
                 while (dr.Read())
                 {
                    lblBsCode.Text = dr["bscode"].ToString();
                    txtBsName.Text = dr["bsname"].ToString();

                 }
                 dr.Close();
                 conn.Close();
              }
           }
       }
 protected void btnSave_Click(object sender, EventArgs e)
    {
           conn.Open();
           string UCODE = LblUcode.Text;
           SqlCommand cmd = new SqlCommand("update users Set uname=@Uname,ushortname=@Ushortname,pswd=HASHBYTES('MD5',@Pswd) where ucode=@UCODE", conn);

           cmd.Parameters.AddWithValue("@Uname",txtUserName.Text );
           cmd.Parameters.AddWithValue("@Ushortname",txtUserShortName.Text );
           cmd.Parameters.AddWithValue("@Pswd",txtPassword.Text );
           cmd.Parameters.AddWithValue("@UCODE", UCODE);
           cmd.ExecuteNonQuery();
           cmd.Dispose();

           ShowMessage("Company Data update Successfully......!");

           clear();
}

感谢您在上述代码的帮助下完成所有工作。

为什么即使没有错误，此UPDATE命令也不会更新数据？

4 个答案: