title: what will rs.getString(1) return if the SQL query returns nothing
body: <p>heres my code :</p>
  
  <p>code for connecting database :</p>
  
  <pre><code>Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
  Connection con=DriverManager.getConnection("jdbc:sqlserver://localhost:1433;databaseName=city_mart;user=sa;password=aptech");
  Statement st=con.createStatement();
  
  String sql="Select Emp_login_ID from employee where Emp_login_ID = '"+r3.getText()+"' ";
  ResultSet rs=st.executeQuery(sql);
  
  String login = rs.getString(1);
  
  if (r3.getText().equalsIgnoreCase(login))
  {
      JOptionPane.showMessageDialog(rootPane, "Login ID not available.");
  }
  else
  {
      JOptionPane.showMessageDialog(rootPane, "Login ID is available.");
  }
  </code></pre>
  
  <p>thanks.any help is much appreciated.</p>