如何给出正确的错误信息

本文关键字：错误 信息 | 更新日期: 2023-09-27 18:17:38

根据我的代码"您的密码已被成功更改!，祝贺你!"消息弹出，即使更新没有工作。如果更新没有发生，我怎么能给出错误信息(似乎我的更新语句中也有错误……)。实际上，我无法想象如何在这里使用if语句。

    protected void Button1_Click(object sender, EventArgs e)
    {
        MySqlConnection connection = new MySqlConnection("server=localhost; database=e-learningsystem; uid=root; password=123;port=3307;");
        connection.Open();
         try
         {
             MySqlCommand cmd1 = new MySqlCommand("UPDATE student Set Password= '" + TextBox3.Text + "' WHERE UserName='" + TextBox1.Text + "' AND Password='"+TextBox2.Text+"'", connection);
             cmd1.ExecuteNonQuery();
             Response.Write(@"<script language='javascript'>alert('Your Password Has Been Changed successfully!, Congratulations!')</script>");
             connection.Close();
            }
         catch (Exception ex)
           {
             Response.Write(@"<script language='javascript'>alert(ex.Message)</script>");
            }
    }

如何给出正确的错误信息

cmd1.ExecuteNonQuery()返回受影响的行数。因此，如果你的查询更新了任何记录，那么它将返回超过0行(在本例中为该用户的1行)所以试试这个

if(cmd1.ExecuteNonQuery()>0)
{
   // successfull 
}
else
{ 
  // failure
}

和请不要在您的查询中传递这样的值。尝试使用SqlParameter在查询中传递参数，以避免Sql Injection。

Sachin's Answer为您的消息框弹出问题提供解决方案。

但是为什么要实现自己的认证机制?有什么理由不使用asp.net成员提供程序吗?

假设你有很好的理由这样做。但是，如果您正在实现自定义身份验证，请检查此示例成员资格提供程序实现

例如ChangePassword方法:

public override bool ChangePassword(string username, string oldPwd, string newPwd)
{
    // validate the user first, you are not doing any validation 
    // logged in user can change any other users password in your approach 
    if (!ValidateUser(username, oldPwd))
    return false;
    //new password validation and giving proper message if failed 
    // skip this code from given link
    // use parameterized query as below 
    OdbcConnection conn = new OdbcConnection(connectionString);
    OdbcCommand cmd = new OdbcCommand("UPDATE Users "  +
          " SET Password = ?, LastPasswordChangedDate = ? " +
          " WHERE Username = ? AND ApplicationName = ?", conn);
    cmd.Parameters.Add("@Password", OdbcType.VarChar, 255).Value = EncodePassword(newPwd);
    cmd.Parameters.Add("@LastPasswordChangedDate", OdbcType.DateTime).Value = DateTime.Now;
    cmd.Parameters.Add("@Username", OdbcType.VarChar, 255).Value = username;
    cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = pApplicationName;

    int rowsAffected = 0;
    try
    {
        conn.Open();
            // this is how you can check whether row updated or not 
        rowsAffected = cmd.ExecuteNonQuery();
    }
    catch (OdbcException e)
    {
        // you need to have proper error handling as well 
        if (WriteExceptionsToEventLog)
        {
          WriteToEventLog(e, "ChangePassword");
          throw new ProviderException(exceptionMessage);
        }
        else
        {
          throw e;
        }
    }
    finally
    {
        conn.Close();
    }
    if (rowsAffected > 0)
    {
        return true;
    }
    return false;
}
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