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Unable to view message if wrong data enter or null data enter

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Unable to view message if wrong data enter or null data enter

 
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  #1
Sep 21st, 2008
Hi,
I have created a login form that has adminid and password..
I use visual studio 2005,database access.
login form work smoothly when i enter the correct adminid and password but never display an error message if wrong data was entered or no data was entered.
I need a help on this.
Along with this i show my coding.
Hope somebody will help me..

C# Syntax (Toggle Plain Text) 
  1.       private void button1_Click(object sender, EventArgs e)
  2.         {
  3.             String admId = textBox1.Text;
  4.             String passw = textBox2.Text;
  5.  
  6.             OleDbConnection conn = new OleDbConnection("provider = microsoft.jet.oledb.4.0;data source = dbStd.mdb;");
  7.             try
  8.             {
  9.                 conn.Open();
  10.             }
  11.             catch(Exception db)
  12.             {
  13.                 MessageBox.Show("Error accessing the database: " + db.Message);
  14.             }
  15.  
  16.             OleDbCommand command = new OleDbCommand();
  17.             command.Connection = conn;
  18.             command.CommandText = "SELECT AdminId,Password FROM Admin WHERE AdminId ='"+admId+"'AND Password = '"+passw+"'";
  19.  
  20.             OleDbDataReader datareader = command.ExecuteReader();
  21.  
  22.  
  23.                 while (datareader.Read()== true)
  24.                 {
  25.  
  26.                         string autAdmin = datareader.GetString(0);
  27.                         string autPass = datareader.GetString(1);
  28.  
  29.                         if (admId == autAdmin && passw == autPass)
  30.                         {
  31.                             MessageBox.Show("Welcome!");
  32.  
  33.                         }
  34.                         else if (admId == "" || passw == "")
  35.                         {
  36.                             MessageBox.Show("Try Again");
  37.                         }
  38.  
  39.                 }            
  40.                 datareader.Close();
  41.                 conn.Close();
  42.  
  43.  
  44.  
  45.         }
Last edited by cscgal; Sep 21st, 2008 at 2:47 am. Reason: Added code tags
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Re: Unable to view message if wrong data enter or null data enter

 
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  #2
Sep 21st, 2008
If you dont enter any it doesnt find a record in the db so no it wont show a message (debugging would show you this as the records returned would be none)

set a flag at the top of the routine to false
if you get a valid login, set it true, if its still false when you get to the bottom then they didnt have a valid id
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Re: Unable to view message if wrong data enter or null data enter

 
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  #3
Sep 22nd, 2008
Thank for replying my thread..
Actually i'm still new in c# and don't know how to use the flag..
really need your help..
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Re: Unable to view message if wrong data enter or null data enter

 
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  #4
Sep 22nd, 2008
Create a boolean variable, thats a "flag" as its yes or no.
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Re: Unable to view message if wrong data enter or null data enter

 
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  #5
Sep 22nd, 2008
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Originally Posted by shxrainz View Post
Hi,
I have created a login form that has adminid and password..
I use visual studio 2005,database access.
login form work smoothly when i enter the correct adminid and password but never display an error message if wrong data was entered or no data was entered.
I need a help on this.
Along with this i show my coding.
Hope somebody will help me..

C# Syntax (Toggle Plain Text) 
  1.       private void button1_Click(object sender, EventArgs e)
  2.         {
  3.             String admId = textBox1.Text;
  4.             String passw = textBox2.Text;
  5.  
  6.             OleDbConnection conn = new OleDbConnection("provider = microsoft.jet.oledb.4.0;data source = dbStd.mdb;");
  7.             try
  8.             {
  9.                 conn.Open();
  10.             }
  11.             catch(Exception db)
  12.             {
  13.                 MessageBox.Show("Error accessing the database: " + db.Message);
  14.             }
  15.  
  16.             OleDbCommand command = new OleDbCommand();
  17.             command.Connection = conn;
  18.             command.CommandText = "SELECT AdminId,Password FROM Admin WHERE AdminId ='"+admId+"'AND Password = '"+passw+"'";
  19.  
  20.             OleDbDataReader datareader = command.ExecuteReader();
  21.  
  22.  
  23.                 while (datareader.Read()== true)
  24.                 {
  25.  
  26.                         string autAdmin = datareader.GetString(0);
  27.                         string autPass = datareader.GetString(1);
  28.  
  29.                         if (admId == autAdmin && passw == autPass)
  30.                         {
  31.                             MessageBox.Show("Welcome!");
  32.  
  33.                         }
  34.                         else if (admId == "" || passw == "")
  35.                         {
  36.                             MessageBox.Show("Try Again");
  37.                         }
  38.  
  39.                 }            
  40.                 datareader.Close();
  41.                 conn.Close();
  42.  
  43.  
  44.  
  45.         }
Hello,

C# Syntax (Toggle Plain Text) 
  1. if (admId == autAdmin && passw == autPass)
  2.                         {
  3.                             MessageBox.Show("Welcome!");
  4.  
  5.                         }
  6.                         else if (admId == "" || passw == "")
  7.                         {
  8.                             MessageBox.Show("Try Again");
  9.                         }

this code means if you enter correct adminid and pass then it`ll show you welcome msg but it will show try again msg only if both fields are blank.

C# Syntax (Toggle Plain Text) 
  1. if (admId == autAdmin && passw == autPass)
  2.                         {
  3.                             MessageBox.Show("Welcome!");
  4.  
  5.                         }
  6.                         else
  7.                         {
  8.                             MessageBox.Show("Try Again");
  9.                         }

try this one. working fine from my end.

Regards,
Puneet Kalra
www.PuneetK.com
Sun Certified Java Programmer

Admin of Pikk - Object Relational Mapping Framework
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Re: Unable to view message if wrong data enter or null data enter

 
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  #6
Sep 23rd, 2008
It still doesn't work..
The message for "try again" didn't pop up when no data enter or wrong data enter..

Can i have the syntax of Boolean flag?
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Re: Unable to view message if wrong data enter or null data enter

 
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  #7
Sep 23rd, 2008
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Originally Posted by shxrainz View Post
It still doesn't work..
The message for "try again" didn't pop up when no data enter or wrong data enter..

Can i have the syntax of Boolean flag?
It works when correct details are entered ?

I checked it again and working fine with me.

Regards,
Puneet Kalra
www.PuneetK.com
Sun Certified Java Programmer

Admin of Pikk - Object Relational Mapping Framework
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Re: Unable to view message if wrong data enter or null data enter

 
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  #8
Sep 23rd, 2008
i already can view the "try again message box" with just editing the SELECT statement..
but then another problem arise..

the message box keep pop up until all the data in the database being checked..
i try to do switch statement..
but got an error..
in mydatabase,i already have 3 data..
and the message keep view for 3 times until it finish looping..

can anyone help me?

this is the current code i being used:

OleDbCommand cmd = new OleDbCommand();
cmd.Connection = conn;
cmd.CommandText = "SELECT AdminId,Password FROM Admin"; //WHERE AdminId = '"+admId+"' AND Password = '"+passw+"'";

OleDbDataReader DtReader = cmd.ExecuteReader();



while(DtReader.Read())
{
string autAdmin = DtReader.GetString(0);
string autPass = DtReader.GetString(1);


if(admId == autAdmin && passw == autPass)
{
MessageBox.Show("Welcome");
}
else
{
MessageBox.Show("Try Again");
}

}
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Re: Unable to view message if wrong data enter or null data enter

 
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  #9
Sep 23rd, 2008
Firstly if you did a correct selection from the db, it would return 1 line that matched or 0, it shouldnt do it for all users in the db.

Secondly, if you created a flag to equate to "found" or "not found" you could then deal with it at the end. So even if you did have multiple entries loops through for some odd reason, you would only display one message.
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Re: Unable to view message if wrong data enter or null data enter

 
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  #10
Sep 23rd, 2008
try this one...
Don't limit the "try catch" the error will occur anytime so its best to put all your codes in a try catch block.


C# Syntax (Toggle Plain Text) 
  1. private void button1_Click(object sender, EventArgs e)
  2. {
  3.       string admId = textBox1.Text;
  4.       string passw = textBox2.Text;
  5.       string strqry = string.Format(@"SELECT AdminId,Password 
  6.                                                     FROM    Admin 
  7.                                                     WHERE  AdminId ={0} AND 
  8.                                                                 Password = {1}", admId,  passw);
  9.  
  10.       OleDbConnection conn = new OleDbConnection("provider=microsoft.jet.oledb.4.0;data  
  11.                                                                              source=dbStd.mdb;");
  12.       OleDbDataAdapater adapter = null;
  13.       try
  14.       {
  15.              conn.Open();
  16.              adapter = new OleDbDataAdapter(strqry, conn.ConnectionString);
  17.              adapter.Fill(dt);
  18.  
  19.              if (dt.Rows.Count >0)    
  20.              {
  21.                   string username = dt.Rows[0][0].ToString();
  22.                   string pw = dt.Rows[0][1].ToString();
  23.  
  24.                   if (username == admId && pw == passw)
  25.                   {
  26.                         MessageBox.Show("Welcome!");
  27.                   }
  28.                   else
  29.                   {
  30.                         MessageBox.Show("Access Denied.");
  31.                   }
  32.              }
  33.              else
  34.              {
  35.                      MessageBox.Show("Access Denied.");
  36.              }
  37.  
  38.        }
  39.        catch (Exception exc)
  40.        {
  41.               MessageBox.Show(exc.ToString());
  42.        }
  43.        finally
  44.        {
  45.              adapter.Dispose();
  46.              adapter.Close();
  47.              conn.Close();
  48.        }
A conclusion is the place where you got tired of thinking.
http://www.martin2k.co.uk/forums/index.php?showforum=4
http://www.a1vbcode.com/a1vbcode/vbforums/Forum3-1.aspx
http://www.developerfusion.co.uk/for...orum&ForumID=4
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