Hi

I am using web application.

on my login button i have written this code

protected void btnlogin_Click(object sender, EventArgs e)
    {
        //sql connection
        SqlConnection cnn = new SqlConnection();
        cnn.ConnectionString = "Server=HOME-PC;Database=kandivalideal;Trusted_Connection=True;";
        cnn.Open();
        SqlCommand cmd = new SqlCommand("select mobileno, password from register where mobileno='"+txtmoblie.Text +"'and password='"+txtpassword.Text+"'",cnn);
        cmd.Connection = cnn;
        SqlDataReader dr = cmd.ExecuteReader();

        if (txtmoblie.Text != "mobileno" && txtpassword.Text != "password")
        {
            Response.Write(@"<script language='javascript'>alert('Invalid Username and Password')</script>");
        }
        else
        {
            Response.Redirect("signup.aspx");
        }
        cnn.Close();
       


    }

I think my If statement is giving me error it is not getting moblie no and password it is giving error by say invalid username and password

You're not using the data extracted in your datareader at all. You are setting up the connection and calling the executeReader method then leaping into the If statement. It is generating the error because you haven't entered "mobileno" and "password" into the two textboxes.

You need to check if the datareader has one row. If it does your SQL statement worked and the user can log in.

Can you give me some example for this please


You're not using the data extracted in your datareader at all. You are setting up the connection and calling the executeReader method then leaping into the If statement. It is generating the error because you haven't entered "mobileno" and "password" into the two textboxes.

You need to check if the datareader has one row. If it does your SQL statement worked and the user can log in.

protected void btnlogin_Click(object sender, EventArgs e)
    {
        //sql connection
        SqlConnection cnn = new SqlConnection();
        cnn.ConnectionString = "Server=HOME-PC;Database=kandivalideal;Trusted_Connection=True;";
        cnn.Open();
        SqlCommand cmd = new SqlCommand("select mobileno, password from register where mobileno='"+txtmoblie.Text +"'and password='"+txtpassword.Text+"'",cnn);
        cmd.Connection = cnn;
        SqlDataReader dr = cmd.ExecuteReader();

        if (dr.Read())
        {
            Response.Redirect("http://www.google.com");
        }
        else
        {
            Response.Write(@"<script language='javascript'>alert('Invalid Username and Password')</script>");
            
        }
        cnn.Close();
       


    }

Edited 4 Years Ago by __avd: Correct [code] tags.

You have assign the value read from datareader to a temp string and then you can check with your database string as you have done.:-) ( the prob you have to sort is datareader value.)

if you do something like the following example the COUNT() function will count the amount of rows within the database that match the WERE clause and return that number. Then you check the number is 0 or not and grant or deny access accordingly.

"SELECT COUNT(*) my MyTable WHERE Username = ' + textbox1.text + ' AND Password = ' + textbox2.text + '";

samply, you execute a SQL statement that select all the ID's from your table that meet the condition:
WHERE Username = ' + textbox1.text + ' AND Password = ' + textbox2.text
if the user is exist and the password is correct you should get one row in the datareader Else the datareder.Read() method will return null.

then ... after you execute the command check: if (!Datareader.Read()) that mean No rows, thus, no users or password not valid!

if you do something like the following example

Sorry i missed the FROM clause out:

"SELECT COUNT(*) FROM MyTable WHERE Username = ' + textbox1.text + ' AND Password = ' + textbox2.text + '";

Edited 3 Years Ago by Dani: Formatting fixed

Everyone's code here is ok from a login point but they all include the textbox text directly in the SQL statement. That is bad, it allows for SQL injection attacks. In the interests of becoming a better code get used to using the parameters of the command object to encapsulate the inputs

MySqlCommand cmd = new MySqlCommand();
cmd.Parameters.Add("?userName", MySqlDataType.Varchar);
cmd.Parameters["?userName"].Value = Textbox1.Text;

Repeat that for the password textbox. It prevents users from slipping in SQL code that can subvert your security.

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