title: distinct with multiple fields and with where condition in mongodb
body: <p>I want to write a query equivalent to <code>distinct</code> and <code>where</code> in <code>mongodb</code>. the sql query is  <code>select DISTINCT key,score from GPC where note="test2" and notetwo = "meet2"</code></p>
  
  <pre><code>{ "_id" : ObjectId("4dc86fef6a0aa8513ab5f21c"), "key" : "SAGAR","score" : 16, "note" : "test1", "notetwo" : "meet1" } 
  { "_id" : ObjectId("4dc86ffd6a0aa8513ab5f21d"), "key" : "SAGAR456", "score" : 17, "note" : "testjh1", "notetwo" : "meetjh1" } 
  { "_id" : ObjectId("4dc8700b6a0aa8513ab5f21e"), "key" : "SAGAR33", "score" : 37, "note" : "test2", "notetwo" : "meet2" } 
  { "_id" : ObjectId("4dc871686a0aa8513ab5f21f"), "key" : "SAGAR33", "score" : 37, "note" : "test2", "notetwo" : "meet2" } 
  { "_id" : ObjectId("4dc871696a0aa8513ab5f220"), "key" : "SAGAR33", "score" : 37, "note" : "test2", "notetwo" : "meet2" } 
  { "_id" : ObjectId("4dc8716c6a0aa8513ab5f221"), "key" : "SAGAR456", "score" : 17, "note" : "testjh1", "notetwo" : "meetjh1" } 
  </code></pre>
  
  <p>Expected result from the query is</p>
  
  <blockquote>
    <p>[{"key" : "SAGAR33", "score" : 37}] </p>
  </blockquote>
  
  <p>What is the equivalent query in <code>mongodb</code>. I am using mongoose to execute queries.</p>