Login Details Code Error

Mohamed Rafi

Sir, I have studied and tried to put login page but it shows code error please tell me the correction sir
It shows error: System.InvalidOperationException: 'The connection is already and also code error

private void button14_Click(object sender, EventArgs e)
{
if (textBox9.Text != "" && textBox10.Text != "")
{
string connectionString;
MySqlConnection cnn;
connectionString = @"Data Source=localhost;Initial Catalog=testDB;User ID=root;Password=mysql";
cnn = new MySqlConnection(connectionString);
cnn.Open();
string id = textBox9.Text;
string password = textBox10.Text;
textBox9.Text = "";
textBox10.Text = "";
string query = "select * from login where userid=@userid,password=@password,confirmpassword=@confirmpassword where loginid=@loginid is same";
//string query = "update employee set employee_name=@employee_name,employee_salary=@employee_salary where employee_id=@employee_id";
using (MySqlCommand cmd = new MySqlCommand(query))
{
cmd.Parameters.AddWithValue("@userid", id);
//cmd.Parameters.AddWithValue("@employee_id", Convert.ToInt32(id));
cmd.Parameters.AddWithValue("@password", password);
//cmd.Parameters.AddWithValue("@confirmpassword", confirmpassword);
cmd.Connection = cnn;
cnn.Open();
cmd.ExecuteNonQuery();
DialogResult dr = MessageBox.Show("Are you sure to Login now?", "Confirmation", MessageBoxButtons.YesNo);
if (dr == DialogResult.Yes)
{
MessageBox.Show("Login Successfully");
cnn.Close();
this.Hide();
Form2 f2 = new Form2();
f2.ShowDialog();
}
else if (dr == DialogResult.No)
{
MessageBox.Show("Please Enter Correct Login details");
}
}
}
else
{
MessageBox.Show("Please Enter details to Login");
}
}
}

8 Replies

Know the answer? Post it — somebody with the same question will find it here.

Sachin Singh4y ago
Accepted answer
Ohhh, correct.
string OriginalPassword=string.Empty;
string query = "select Password from login where userid=@userid";
using (MySqlCommand cmd = new MySqlCommand(query,cnn))
{
cmd.Parameters.AddWithValue("@userid", id);

cmd.Connection = cnn;
cnn.Open();
var psd= cmd.ExecuteScalar();

if (psd!= null)
{
    OriginalPassword= psd.ToString();
}

}

if(txtPassword.Text==txtConfirmPassword.Text && txtPassword.Text==OriginalPassword)
{


DialogResult dr = MessageBox.Show("Are you sure to Login now?", "Confirmation", MessageBoxButtons.YesNo);
if (dr == DialogResult.Yes)
{
MessageBox.Show("Login Successfully");
cnn.Close();
this.Hide();
Form2 f2 = new Form2();
f2.ShowDialog();
}
else if (dr == DialogResult.No)
{
MessageBox.Show("Please Enter Correct Login details");
}

}
else
{
MessageBox.Show("Please Enter details to Login");
}

}

}else
{
MessageBox.Show("Password and Confirm Password field doesn't match");
}
+2
Sachin Singh4y ago
Exact Code:-
These are the steps
1. fetch password of user based on his ID
2.Match the Entered Password with the Password fetched in previous step.
if both are same user is valid else is not valid.
private bool IsValid(int Id, string EnteredPassword)
{
string query = "select Password from Login where userid=@userid";
using (MySqlCommand cmd = new MySqlCommand(query,cnn))
{
cmd.Parameters.AddWithValue("@userid", id);
cmd.Connection = cnn;
cnn.Open();
var psd= cmd.ExecuteScalar();
if (psd!= null)
{
OriginalPassword= psd.ToString();
}
}
return EnteredPassword==OriginalPassword;

}
private void button14_Click(object sender, EventArgs e)

{

if (textBox9.Text != "" && textBox10.Text != "")

{
if(IsValid(Convert.ToInt32(textBox9.Text),textBox10.Text))
{
DialogResult dr = MessageBox.Show("Are you sure to Login now?", "Confirmation Message", MessageBoxButtons.YesNo);

if (dr == DialogResult.Yes)

{

MessageBox.Show("Login Successfully");

this.Hide();

Form2 f2 = new Form2();

f2.ShowDialog();

}

else if (dr == DialogResult.No)

{

MessageBox.Show("Please Enter Correct Login details");

}
}
else

{

MessageBox.Show("Invalid credentials");

}

}
else

{

MessageBox.Show("Please Enter your credentials");

}
}
+2
Mohamed Rafi4y ago
Please give exact my code; i got some expected issues in your code i cant able to run your code so pls give

private void button14_Click(object sender, EventArgs e)

{

if (textBox9.Text != "" && textBox10.Text != "")

{

string connectionString;

MySqlConnection cnn;

connectionString = @"Data Source=localhost;Initial Catalog=testDB;User ID=root;Password=mysql";

cnn = new MySqlConnection(connectionString);

string id = textBox9.Text;

string password = textBox10.Text;

textBox9.Text = "";

textBox10.Text = "";

string query = "select * from login where userid='"+id+"' and password='"+ password + "'";

using (MySqlCommand cmd = new MySqlCommand(query))

{

cmd.Parameters.AddWithValue("@userid", id);

//MessageBox.Show("userid"+ @userid);

cmd.Parameters.AddWithValue("@password", password);

cmd.Connection = cnn;

cnn.Open();

cmd.ExecuteNonQuery();

DialogResult dr = MessageBox.Show("Are you sure to Login now?", "Confirmation Message", MessageBoxButtons.YesNo);

if (dr == DialogResult.Yes)

{

MessageBox.Show("Login Successfully");

cnn.Close();

this.Hide();

Form2 f2 = new Form2();

f2.ShowDialog();

}

else if (dr == DialogResult.No)

{

MessageBox.Show("Please Enter Correct Login details");

}

}

}

else

{

MessageBox.Show("Please Enter With Correct Login Details");

}

}
+2
Mohamed Rafi4y ago
how to check in mysql query that i sotred value userid and password having in database or not?
+2
Mohamed Rafi4y ago
Sir,

This code is right but if i enter wrong userid password means it is loggin in, but it should not login with wrong userid password

private void button14_Click(object sender, EventArgs e)
{
if (textBox9.Text != "" && textBox10.Text != "")
{
string connectionString;
MySqlConnection cnn;
connectionString = @"Data Source=localhost;Initial Catalog=testDB;User ID=root;Password=mysql";
cnn = new MySqlConnection(connectionString);
string id = textBox9.Text;
string password = textBox10.Text;
textBox9.Text = "";
textBox10.Text = "";
string query = "select * from login where userid=@userid and password=@password";
using (MySqlCommand cmd = new MySqlCommand(query))
{
cmd.Parameters.AddWithValue("@userid", id);
cmd.Parameters.AddWithValue("@password", password);
cmd.Connection = cnn;
cnn.Open();
cmd.ExecuteNonQuery();
DialogResult dr = MessageBox.Show("Are you sure to Login now?", "Confirmation", MessageBoxButtons.YesNo);
if (dr == DialogResult.Yes)
{
MessageBox.Show("Login Successfully");
cnn.Close();
this.Hide();
Form2 f2 = new Form2();
f2.ShowDialog();
}
else if (dr == DialogResult.No)
{
MessageBox.Show("Please Enter Correct Login details");
}
}
}
else
{
MessageBox.Show("Please Enter With Correct Login Details");
}
}

+2
Sachin Singh4y ago
test this
string query = "select * from login where userid=@userid,password=@password";
if(txtPassword.Text==txtConfirmPassword.Text)
{
using (MySqlCommand cmd = new MySqlCommand(query,cnn))
{
cmd.Parameters.AddWithValue("@userid", id);
cmd.Parameters.AddWithValue("@password", password);
cmd.Connection = cnn;
cnn.Open();
cmd.ExecuteNonQuery();
DialogResult dr = MessageBox.Show("Are you sure to Login now?", "Confirmation", MessageBoxButtons.YesNo);
if (dr == DialogResult.Yes)
{
MessageBox.Show("Login Successfully");
cnn.Close();
this.Hide();
Form2 f2 = new Form2();
f2.ShowDialog();
}
else if (dr == DialogResult.No)
{
MessageBox.Show("Please Enter Correct Login details");
}
}
}
else
{
MessageBox.Show("Please Enter details to Login");
}
}
}

}else
{
MessageBox.Show("Password and Confirm Password field doesn't match");
}
+2
Mohamed Rafi4y ago
Sir mysql command was not succeeded, when i am giving wrong userid passwor dit shows login successfull i think sql query to be change

if (textBox9.Text != "" && textBox10.Text != "")
{
string connectionString;
MySqlConnection cnn;
connectionString = @"Data Source=localhost;Initial Catalog=testDB;User ID=root;Password=mysql";
cnn = new MySqlConnection(connectionString);
//cnn.Open();
string id = textBox9.Text;
string password = textBox10.Text;
string loginid = "";
textBox9.Text = "";
textBox10.Text = "";
string query = "select * from login where userid=@userid and password=@password and loginid=@loginid";
using (MySqlCommand cmd = new MySqlCommand(query))
{
cmd.Parameters.AddWithValue("@userid", id);
//cmd.Parameters.AddWithValue("@employee_id", Convert.ToInt32(id));
cmd.Parameters.AddWithValue("@password", password);
cmd.Parameters.AddWithValue("@loginid", loginid);
//cmd.Parameters.AddWithValue("@confirmpassword", confirmpassword);
cmd.Connection = cnn;
cnn.Open();
cmd.ExecuteNonQuery();
DialogResult dr = MessageBox.Show("Are you sure to Login now?", "Confirmation", MessageBoxButtons.YesNo);
if (dr == DialogResult.Yes)
{
MessageBox.Show("Login Successfully");
cnn.Close();
this.Hide();
Form2 f2 = new Form2();
f2.ShowDialog();
}
else if (dr == DialogResult.No)
{
MessageBox.Show("Please Enter Correct Login details");
}
}
}
else
{
MessageBox.Show("Please Enter details to Login");
}
}
+2
Jignesh Kumar4y ago
Hi,

You are trying to open connection multiple time, please use below code, remove cnn.Open(); from top.
private void button14_Click(object sender, EventArgs e)
{
if (textBox9.Text != "" && textBox10.Text != "")
{
string connectionString;
MySqlConnection cnn;
connectionString = @"Data Source=localhost;Initial Catalog=testDB;User ID=root;Password=mysql";
cnn = new MySqlConnection(connectionString);

string id = textBox9.Text;
string password = textBox10.Text;
textBox9.Text = "";
textBox10.Text = "";
string query = "select * from login where userid=@userid,password=@password,confirmpassword=@confirmpassword where loginid=@loginid is same";
//string query = "update employee set employee_name=@employee_name,employee_salary=@employee_salary where employee_id=@employee_id";
using (MySqlCommand cmd = new MySqlCommand(query))
{
cmd.Parameters.AddWithValue("@userid", id);
//cmd.Parameters.AddWithValue("@employee_id", Convert.ToInt32(id));
cmd.Parameters.AddWithValue("@password", password);
//cmd.Parameters.AddWithValue("@confirmpassword", confirmpassword);
cmd.Connection = cnn;
cnn.Open();
cmd.ExecuteNonQuery();
DialogResult dr = MessageBox.Show("Are you sure to Login now?", "Confirmation", MessageBoxButtons.YesNo);
if (dr == DialogResult.Yes)
{
MessageBox.Show("Login Successfully");
cnn.Close();
this.Hide();
Form2 f2 = new Form2();
f2.ShowDialog();
}
else if (dr == DialogResult.No)
{
MessageBox.Show("Please Enter Correct Login details");
}
}
}
else
{
MessageBox.Show("Please Enter details to Login");
}
}
}
+2