1

我使用 if else 语句在我的程序中检查了这个错误。我有两件事要检查。他们是

  1. 警察ID(PK)

  2. 身份证

下面的语句检查文本框是否具有与数据库中相同的 PoliceID 和 NRIC 值。

if (tbpid.Text.Equals(dr["policeid"].ToString().Trim()) && (tbnric.Text.Equals(dr["nric"].ToString().Trim())))
                {

                    lbmsg.Text = "This police account has already exist. Please verify the details again.";

                }

如果文本框（警察 id）与数据库中的值相同，它们将给出另一个不同的错误。

 if (tbpid.Text.Equals(dr["policeid"].ToString()))
                {
                    lbmsg.Text = "This police ID has already exists. Please generate another Police ID";
                }

如果文本框 (NRIC) 与数据库中的值相同，则会出现另一个错误

if (tbnric.Text.Equals(dr["nric"].ToString()))
                {
                    lbmsg.Text  ="This NRIC has already exist. Please ensure that the NRIC is correct";
                }

如果我将所有错误检查消息组合在一起，它将是这样的。

 protected void btnAdd_Click(object sender, EventArgs e)
    {



            SqlConnection con = new SqlConnection("Data Source = localhost; Initial Catalog = MajorProject; Integrated Security= SSPI");
            con.Open();
            SqlCommand select = new SqlCommand("Select policeid, nric from PoliceAccount where policeid = @policeid" , con);
            SqlDataReader dr;

            select.Parameters.AddWithValue("@policeid", tbpid.Text);            

            dr = select.ExecuteReader();
            if(dr.Read())
            {
                if (tbpid.Text.Equals(dr["policeid"].ToString().Trim()) && (tbnric.Text.Equals(dr["nric"].ToString().Trim())))
                {

                    lbmsg.Text = "This police account has already exist. Please verify the details again.";

                }
                else if (tbpid.Text.Equals(dr["policeid"].ToString()))
                {
                    lbmsg.Text = "This police ID has already exists. Please generate another Police ID";
                }
                else if (tbnric.Text.Equals(dr["nric"].ToString()))
                {
                    lbmsg.Text  ="This NRIC has already exist. Please ensure that the NRIC is correct";
                }

            }

            else
            {

                SqlConnection conn = new SqlConnection("Data Source = localhost; Initial Catalog = MajorProject; Integrated Security= SSPI");
                conn.Open();
                SqlCommand cmd = new SqlCommand("insert into PoliceAccount(policeid, password, nric, fullname, postedto)  values('" + tbpid.Text.Trim() + "','" + tbpid.Text.Trim() + "','" + tbnric.Text.Trim() + "','" + tbfullname.Text.Trim() + "', '" + ddllocation.SelectedValue + "')", conn);
                cmd.ExecuteNonQuery();
                conn.Close();

                lbmsg.Text = "Congratulations. The police account of ID " + tbpid.Text + " has been successfully added. You may edit the profile via the edit profile tab above";

                tbpid.Text = "";
                tbnric.Text = "";
                tbfullname.Text = "";
                ddllocation.SelectedValue = "Select Location";


            }

            //ConfirmButtonExtender2.ConfirmText = "Are you sure you want to add this Police Account " + tbpid.Text + " ?";
        }

    }

但是这里的问题是，错误检查消息的前两个语句设法工作。不幸的是，身份证没有工作。例如，如果我输入不同的policeID 但相同的身份证，数据仍被插入到数据库中，这意味着它完全忽略了上面的身份证错误检查。我已经看了好几个小时了，我还没有找到问题所在。如果有人可以指导我，将不胜感激。

另外，在我的数据库中，我已将主键设置为policeID，而NRIC只是我数据库中的常规数据列

问候。

4

2 回答 2

1

由于此查询，最后一个不起作用

Select policeid, nric from PoliceAccount where policeid=@policeid 这不会返回任何行，因为 ploiceid 不存在意味着dr.Read()是假的，因为没有要读取的行，所以它直接进入您在数据库中插入数据的 else 部分。所以让它发挥作用。试试这样...

 if(dr.Read())
            {
                if (tbpid.Text.Equals(dr["policeid"].ToString().Trim()) && (tbnric.Text.Equals(dr["nric"].ToString().Trim())))
                {

                    lbmsg.Text = "This police account has already exist. Please verify the details again.";

                }
                else if (tbpid.Text.Equals(dr["policeid"].ToString()))
                {
                    lbmsg.Text = "This police ID has already exists. Please generate another Police ID";
                }
            }

            else
            {
 if (tbnric.Text.Equals(dr["nric"].ToString()))
                {
                    lbmsg.Text  ="This NRIC has already exist. Please ensure that the NRIC is correct";
                }
else
{

                SqlConnection conn = new SqlConnection("Data Source = localhost; Initial Catalog = MajorProject; Integrated Security= SSPI");
                conn.Open();
                SqlCommand cmd = new SqlCommand("insert into PoliceAccount(policeid, password, nric, fullname, postedto)  values('" + tbpid.Text.Trim() + "','" + tbpid.Text.Trim() + "','" + tbnric.Text.Trim() + "','" + tbfullname.Text.Trim() + "', '" + ddllocation.SelectedValue + "')", conn);
                cmd.ExecuteNonQuery();
                conn.Close();

                lbmsg.Text = "Congratulations. The police account of ID " + tbpid.Text + " has been successfully added. You may edit the profile via the edit profile tab above";

                tbpid.Text = "";
                tbnric.Text = "";
                tbfullname.Text = "";
                ddllocation.SelectedValue = "Select Location";
}
}

要使您的现有代码正常工作，请尝试此查询

Select policeid, nric from PoliceAccount where policeid=@policeid or nric=@nric

如果其中一个 id 存在于数据库中，如果两者都不存在，它将始终返回行，而不是将其插入到数据库中。

于 2013-07-29T07:10:56.693 回答
1

您的 select 语句似乎是问题所在。似乎您也希望 nric 是唯一的，但您没有在 select 语句的 where 子句中使用它。你现在拥有它的方式，只要policyid是唯一的，任何nric值都可以。换句话说，如果前两个检查通过，那么第三个检查也将通过。试试这个：

SqlCommand select = new SqlCommand("Select policeid, nric from PoliceAccount where policeid = @policeid or nric = @nric" , con);
SqlDataReader dr;

select.Parameters.AddWithValue("@policeid", tbpid.Text);
select.Parameters.AddWithValue("@nric", tbnric.Text);

dr = select.ExecuteReader();

但是，如果您不希望 nric 是唯一的，那么您的代码可以正常工作！

于 2013-07-29T07:22:09.540 回答