title: How to concatenate two rows into one in Oracle?
body: <p>I have a table which has such kind of records</p>
  
  <pre><code>ID wk category mo tu wedn
  1   1   3       4   4  4
  1   1   4       5   5  5
  1   1   18      7   7  7
  1   2   3       4   4  4
  1   2   4       5   5  5
  1   2   17      2   2  2
  </code></pre>
  
  <p>How do I concatenate rows have same category and keep the non-matched rows from either wk=1 and wk=2 as well into something like the following
  and data from wk=1 are required in from of data from wk=2:</p>
  
  <pre><code>ID  category mo tu wedn mo2 tu2 wedn2
  1       3    4   4   4   4   4   4
  1       4    5   5   5   5   5   5
  1       18   7   7   7   0   0   0
  1       17   0   0   0   2   2   2
  </code></pre>
  
  <p>Thanks,</p>