title: How merge three DataFrame in Scala
body: <p>How merge 3 DataFrame in Spark-Scala? I completly don't have any Idea how I can make this. On stackOverFlow I can't found similar example.</p>
  
  <p>I have 3 similar DataFrames. The same name of Column, and the same number of them. Difference is only a value on rows.</p>
  
  <h3>DataFrame1:</h3>
  
  <pre><code>+----+------+----+---+
  |type| Model|Name|ID |
  +----+------+----+---+
  |  1 |wdasd |xyzd|111|
  |  1 |wd    |zdfd|112|
  |  1 |bdp   |2gfs|113|
  +----+------+----+---+
  </code></pre>
  
  <h3>DataFrame2:</h3>
  
  <pre><code>+----+------+----+---+
  |type| Model|Name|ID |
  +----+------+----+---+
  |  2 |wdasd |xyzd|221|
  |  2 |wd    |zdfd|222|
  |  2 |bdp   |2gfs|223|
  +----+------+----+---+
  </code></pre>
  
  <h3>DataFrame3:</h3>
  
  <pre><code>+----+------+----+---+
  |type| Model|Name|ID |
  +----+------+----+---+
  |  3 |AAAA  |N_AM|331|
  |  3 |BBBB  |NA_M|332|
  |  3 |CCCC  |MA_N|333|
  +----+------+----+---+
  </code></pre>
  
  <p>And I want to this type of DataFrame</p>
  
  <h3>MergeDataFrame:</h3>
  
  <pre><code>+----+------+----+---+
  |type| Model|Name|ID |
  +----+------+----+---+
  |  1 |wdasd |xyzd|111|
  |  1 |wd    |zdfd|112|
  |  1 |bdp   |2gfs|113|
  |  2 |wdasd |xyzd|221|
  |  2 |wd    |zdfd|222|
  |  2 |bdp   |2gfs|223|
  |  3 |AAAA  |N_AM|331|
  |  3 |BBBB  |NA_M|332|
  |  3 |CCCC  |MA_N|333|
  +----+------+----+---+
  </code></pre>