title: Merge three rows into one row in sql server
body: <p>I have a table where columns name as</p>
  
  <pre><code>[ViewAllLogId] primary key
  [orderNumber]
  [OUTGATEDATE]
  [ARRIVALDATE]
  [COMPLETEDDATE]
  ....etc
  </code></pre>
  
  <p>where for each [orderNumber] it has 3 rows in which one column[e.g OUTGATEDATE] is filled, other columns [e.g ARRIVALDATE and COMPLETEDDATE] are empty.
  I want to merge 3 rows into 1 rows where all 3 column has its own value correspondent to that [orderNumber]</p>