title: text entered in uppercase during login still gives successful login
body: <p>I have a login page for my windows application in c#.even if i enter the username and password in uppercase i.e with CAPS ON still the login is successful.</p>
  
  <p>This should not be the case, as the enteries in the database are in lower case.</p>
  
  <pre><code>public partial class frmlogin : Form
  {
      SqlConnection con = new SqlConnection("Data Source=TH07L019;Initial Catalog=procurement;Integrated Security=True");
      DataTable dt = new DataTable();
      SqlCommand cmd = new SqlCommand();
      SqlDataAdapter adp = new SqlDataAdapter();
  
  
      public frmlogin()
      {
          InitializeComponent();
      }
  
      private void Form1_Load(object sender, EventArgs e)
      {
          cmd.Connection = con;
      }
  
      private void button1_Click(object sender, EventArgs e)
      {
          con.Open();
          cmd.CommandText = "select * from login where username='" + txtusername.Text + "' and password='" + txtpassword.Text + "'";
          adp.SelectCommand = cmd;
          adp.Fill(dt);
          if (dt.Rows.Count &gt; 0)
          {
              frmmain main = new frmmain();
              main.Show();
          }
          else
          {
              MessageBox.Show("Please enter correct name and passowrd", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
              txtusername.Clear();
              txtpassword.Clear();
          }
          con.Close();
      }
  }
  </code></pre>
  
  <p>how to solve this problem</p>