blah blah blah is here! blah blah » Close

0
silentrocker
0
810 views

No Data exists for Rows/Column

up0down
link

The visual c# code returns no data exists for row/column on select * from table even though the data exists

OleDbDataReader dataReader;
OleDbCommand cmd1 = new OleDbCommand("SELECT * FROM username",conn);
MessageBox.Show(conn.ConnectionString);




try
{
//Execute the command store in cmd1 and save the return value in datareader
dataReader = cmd1.ExecuteReader();
MessageBox.Show(dataReader.GetString(0));
if (dataReader.Read())
{
/*if (dataReader.GetString(0) == txtLoginPass.Text)
{
frmWelcome fm = new frmWelcome(this);
txtRegisterUserName.Text = "";
txtRegisterPass.Text = "";
txtLoginUserName.Text = "";
txtLoginPass.Text = "";
txtRegisterConfirmPass.Text = "";
txtLoginUserName.Focus();
this.Hide();
fm.Show();
}*/

if (dataReader.GetString(0) == "admin")
{
MessageBox.Show("Welcome Admin");
}
else if(dataReader.GetString(0) == "under")
{
MessageBox.Show("Welcome.......");
}
else
{
MessageBox.Show("Invalid Username/Password!");
usernameTextBox.Text = "";
passwordTextBox.Text = "";
usernameTextBox.Focus();
}

}
else
{
MessageBox.Show("Invalid Username/Password!");
usernameTextBox.Text = "";
passwordTextBox.Text = "";
usernameTextBox.Focus();
}
dataReader.Close();
}
catch (Exception e1)
{
MessageBox.Show(e1.Message);
}

c# rows columns
  • asked one year ago
add comment
last answered one year ago

1 answers

Sort:
up0down
link

Initially, the record pointer is just before the first record so you need to call the Read() method before you can access the data in the first record.

So try it like this:

OleDbDataReader dataReader;
OleDbCommand cmd1 = new OleDbCommand("SELECT * FROM username",conn);
MessageBox.Show(conn.ConnectionString);

try
{
   //Execute the command store in cmd1 and save the return value in datareader
   dataReader = cmd1.ExecuteReader();

   if (dataReader.Read()) // read first record (use 'while' instead of  'if' to keep accessing records)
   {
      string s = dataReader.GetString(0);

      if (s == "admin")
      {
         MessageBox.Show("Welcome Admin");
      }
      else if(s == "under")
      {
         MessageBox.Show("Welcome.......");
      }
      else
      {
         MessageBox.Show("Invalid Username/Password!");
         usernameTextBox.Text = "";
         passwordTextBox.Text = "";
         usernameTextBox.Focus();
      }

   }
   else
   {
      MessageBox.Show("No records in the database!");
   }
}
catch (Exception e1)
{
   MessageBox.Show(e1.Message);
}
finally
{
   dataReader.Close();
}

  • answered one year ago by:

    vulpes
    17279
  • edited one year ago
(x)
gsvirdi
412

What ecatly are we doing here? I mean I want to know the implication of this code/effort.

(x)
vulpes
17279

The way I read it is that the OP is trying to get the first row from the database and see whether the first column contains 'admin', 'under' or something else and issue the appropriate message. This, of course, is just a test as eventually the OP will want to check the user's name and password with what's in the database and proceed accordingly.

add comment
Feedback