this is login form in c#

Question

3.00/5 (2 votes)

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if part works very well .But the else part has mistakes in it..(what wrong in else part)...

this is my code...please assist me....

C#

SqlConnection con = new SqlConnection(@"Data source=LENOVO-PC\SQLEXPRESS1;Initial catalog=bank;user id=sa;password=123456");
            con.Open();
            SqlCommand cmd = new SqlCommand("select username ,password from login where username='" + textBox1.Text + "' and password='" + textBox2.Text + "'", con);
            SqlDataReader sdr = cmd.ExecuteReader();

            string user = textBox1.Text;
            string pwd = textBox2.Text;
            if (sdr.HasRows)
            {
                while (sdr.Read())
                {

                    if (this.CompareStrings(sdr["password"].ToString(), pwd) && this.CompareStrings(sdr["username"].ToString(), user))
                    {
                        MessageBox.Show("Login");

                    }

                    else
                    {
                        MessageBox.Show("Error");
                    }

                }
            }
            sdr.Close();
            con.Close();

Posted 7-Mar-13 0:52am

GopinathSk

Updated 7-Mar-13 1:05am

v3

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Comments

ridoy 7-Mar-13 6:56am

what mistakes?clear your question..

GopinathSk 7-Mar-13 7:01am

else part is not working......

ZurdoDev 7-Mar-13 6:56am

What do you need?

GopinathSk 7-Mar-13 6:58am

else part is not working......

ZurdoDev 7-Mar-13 7:01am

And what does that mean?

GopinathSk 7-Mar-13 7:11am

this is simple login form....i want,if the user give wrong crediential then it must go for else part...But actually it not goto else....

ZurdoDev 7-Mar-13 7:15am

So, that must mean that this.CompareStrings(sdr["password"].ToString(), pwd) && this.CompareStrings(sdr["username"].ToString(), user) is returning true. Just focus on that.

GopinathSk 7-Mar-13 7:22am

yeah, it correct but if i give wrong one means it doesn't show an error msg

ZurdoDev 7-Mar-13 7:28am

Simply putting breakpoints in your code and stepping through it would have found the issue. See solution 1.

GopinathSk 7-Mar-13 7:01am

else part is not working......

phil.o 7-Mar-13 6:58am

MessageBox.Show("Error");

This is the only code in your 'else' part.
What is the error exactly ? Are we supposed to guess ?

GopinathSk 7-Mar-13 7:00am

i want like that..
if the user give wrong crediantial then else part will execute

phil.o 7-Mar-13 7:02am

Sorry, but it still does not answer the question.

2 solutions

Solution 2

by mistake i put my else part inside the while loop..that's the problem....

here the solution is::

C#

if (sdr.HasRows)
           {
               while (sdr.Read())
               {

                   if (this.CompareStrings(sdr["username"].ToString(), user) && this.CompareStrings(sdr["password"].ToString(), pwd))
                   {
                       MessageBox.Show("Login");
                   }


               }
           }
           else
           {
               MessageBox.Show("Error");
           }

Posted 7-Mar-13 1:33am

GopinathSk

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Manfred Rudolf Bihy · Accepted Answer · 2013-03-07T01:25:00

You'll probably laugh yourself silly when I point it out to you, but here I go anyway:

The "else" part will of course never execute, because the SQL select statement will only return a row from the table login if both the username and the password match.
Since there will only be a row if and when they match you can rewrite your code like this (only the outer if is nescessary):

C#

if (sdr.HasRows) // if it has a row then username and password matched
{
    MessageBox.Show("Login");
}
else             // if there is no row they didn't match
{
    MessageBox.Show("Error");
}

If your datamodel is correct you don't even have to check if there are more than one row.
Please also observe this: Never construct your SQL statements by concatenating strings, use SqlParameters instead.

Regards,

— Manfred

this is login form in c#

2 solutions

Solution 2

Solution 1

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