[yasirh88]

كود :

SqlConnection con = new SqlConnection("Data Source=USER;DataBase=admin;Integrated Security=True"); // making connection  
SqlDataAdapter sda = new SqlDataAdapter("SELECT * FROM login WHERE username='"+ textBox1.Text +"' AND password='"+ textBox2.Text +"'",con);  
sqlDataAdapter mda=new sqldataadapter ("select * from database",con);
DataTable dt = new DataTable();
datatable cc=new datatable();

sda.Fill(dt);
mda.fill(cc);
 

in the load event >>>

listbox1.items.add(cc[].to string());
form1 start=new form1();
start.show();

buttonOpen_click(){  
    this.close();  
     form2 login=new form2();
login.show();
if (dt.Rows[0][0].ToString() == "1")  
  {  
    form3 program=new form3();
program.show();



  }  
  else  {
  MessageBox.Show("Invalid username or password");  
 }
}