title: how can i get Select option value in antd
body: <p>I have two select drop downs. If I click on One select option, it should be select and after click, without clicking second dropdown, i am not suppose to click update button. It should be show error.  </p>
  
  <pre><code>import React from 'react'
  import ReactDOM from 'react-dom'
  import { Select, Button } from 'antd';
  
  const  Option =Select.Option
  
  
  class SelectOption extends React.Component{
      handleTeacherChange=(value)=&gt;{
          console.log(value)
  
      }
      handleCourseChange=(value)=&gt;{
          console.log(value)
  
      }   
      render()
      {
          return(
              &lt;div align="center"&gt;
               &lt;div&gt;
              &lt;h2&gt;Shishu Bharathi&lt;/h2&gt;
              &lt;label&gt;Teacher List :&lt;/label&gt;
              &amp;nbsp;
  
                  &lt;Select defaultValue="Select" style={{ width: 120 }} onChange={this.handleTeacherChange}&gt;
                  &lt;Option value="Vikram"&gt;Vikram&lt;/Option&gt;
                  &lt;Option value="Ramesh"&gt;Ramesh&lt;/Option&gt;
                  &lt;/Select&gt;
  
                  &amp;nbsp;  &amp;nbsp;   
                  &lt;label&gt;Course List :&lt;/label&gt;
              &amp;nbsp;
  
                  &lt;Select defaultValue="Select" style={{ width: 120 }} onChange={this.handleCourseChange}&gt;
                  &lt;Option value="cul1a"&gt;CUL1A&lt;/Option&gt;
                  &lt;Option value="cul1b"&gt;CUL1B&lt;/Option&gt;
                  &lt;/Select&gt;
                  &lt;/div&gt;
                  &lt;br&gt;&lt;/br&gt; 
                  &lt;br&gt;&lt;/br&gt;                
  
                  &lt;Button &gt;Update&lt;/Button&gt;          
              &lt;/div&gt;
          )
      }
  }    
  export default SelectOption
  </code></pre>