title: Check whether a particular node exist in xml data
body: <p>I have an xml data given below. I need to check whether an employee of empName="John" exists in Production department. If exists update the salary otherwise add an employee to the department.</p>
  
  <pre><code> &lt;Company&gt;   
      &lt;Company Name="ABCDEF" /&gt;
      &lt;Place="AKR" /&gt;
      &lt;Production&gt;
         &lt;employee empName="John" empId="E11" salary="1000" /&gt;
         &lt;employee empName="Ivan" empId="E12" salary="3000" /&gt;
         &lt;employee empName="Paul" empId="E13" salary="1200" /&gt;
      &lt;/Production&gt;
      &lt;Marketing&gt;
        &lt;employee empName="Keith" empId="EMP11" /&gt;
        &lt;employee empName="Christina" empId="EMP12" /&gt;
      &lt;/Marketing&gt;
    &lt;/Company&gt;
  </code></pre>
  
  <p>I need to check particular node exist in this data using c# linq?</p>