C# (login form) getting error with db after creating an .exe

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sorry with my english and new to this
im trying to create a login form application with datatable in visualstudio

it works fine in my pc that i created the program with..
but after i create a setup for my laptop it gets me an error after i press login button

pop up window says

Login
X Unhandled exception has occured in your application..-

An attemp to attach an auto-named database for file C:\users\user\Documents\testlogin.mdf failed. A database with the same name exist,
or specified file cannot be opened, or it is located on UNC share.

What I have tried:

Sorry for language

LoginButton

private void btnLogin_Click(object sender, EventArgs e)
       {
           SqlConnection conn = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\iSunner\Documents\testlogin.mdf;Integrated Security=True;Connect Timeout=30");
           SqlDataAdapter sda = new SqlDataAdapter("select count(*) from login where username ='" + TxtUsername.Text + "' and password='" + txtPassword.Text + "'", conn);
           DataTable dt = new DataTable();
           sda.Fill(dt);
           if (dt.Rows[0][0].ToString() == "1")
           {
               this.Hide();
               ListMeja lm = new ListMeja();
               lm.Show();
           }
           else
           {
               MessageBox.Show("Username/password salah", "ADUH!", MessageBoxButtons.OK, MessageBoxIcon.Error);
           }

       }

Posted 18-Aug-18 15:59pm

Muhammad nur Ihsan

Updated 18-Aug-18 19:11pm

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2 solutions

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Member 13292891 · Answer 1 · 2018-08-18T19:11:00

Solution 2

String Query="Select Count(*)from LogInfo where UserName=@uname and PassWord=@pwd;
SqlCoomad cmd=new SqlCoomand(Query,conn);
cmd.Parameter.Add(new SqlParameter("@Uname",Textbox1.Text));
cmd.Parameter.Add(new SqlParameter("@pwd",Textbox2.Text);

Posted 18-Aug-18 19:11pm

Member 13292891

Comments

Muhammad nur Ihsan 19-Aug-18 7:58am

im still getting error can you help to fix?

SqlConnection conn = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\testlogin.mdf;Integrated Security=True;Connect Timeout=30");
String Query = "Select Count(*)from LogInfo where UserName='@Uname" + TxtUsername.Text + "' and password='@pwd" + txtPassword.Text + "'";
SqlCommand cmd = new SqlCommand(Query, conn);
cmd.Parameters.Add(new SqlParameter("@Uname", TxtUsername.Text));
cmd.Parameters.Add(new SqlParameter("@pwd", txtPassword.Text));
DataTable dt = new DataTable();
if (dt.Rows[0][0].ToString() == "1")
{
this.Hide();
ListMeja lm = new ListMeja();
lm.Show();
}

Patrice T · Answer 2 · 2018-08-18T16:08:00

C#

SqlDataAdapter sda = new SqlDataAdapter("select count(*) from login where username ='" + TxtUsername.Text + "' and password='" + txtPassword.Text + "'", conn);

Not a solution to your question, but another problem you have.
Never build an SQL query by concatenating strings. Sooner or later, you will do it with user inputs, and this opens door to a vulnerability named "SQL injection", it is dangerous for your database and error prone.
A single quote in a name and your program crash. If a user input a name like "Brian O'Conner" can crash your app, it is an SQL injection vulnerability, and the crash is the least of the problems, a malicious user input and it is promoted to SQL commands with all credentials.
SQL injection - Wikipedia[^]
SQL Injection[^]
SQL Injection Attacks by Example[^]
PHP: SQL Injection - Manual[^]
SQL Injection Prevention Cheat Sheet - OWASP[^]
How can I explain SQL injection without technical jargon? - Information Security Stack Exchange[^]