title: Firestore where clause for inequality
body: <p>I want to retrieve a value from firestore for in-equality, I know firestore does not support <code>!=</code> operator.
  We have use this  clause <code>where("age", "&lt;", "30").where("age", "&gt;" 30)</code>
  I want to know how i can use this clause if i want to retrieve the value of string</p>
  
  <pre><code>document.where('courseName','&lt;','MBA').where('courseName','&gt;','MBA').get().then(function(querySnapshot){
          querySnapshot.forEach(function(doc){
               var result3 ="Others"
              var result = querySnapshot.size
  })
  })
  </code></pre>
  
  <p>It is showing the value as null</p>