title: SQL select multiple rows into one row
body: <p>I have a table with related data across multiple rows that I need to query as one row IF the meta_key value is in <code>('A', 'B', 'C')</code>.</p>
  
  <pre><code>meta_id | post_id | meta_key | meta_value
  --------+---------+----------+-----------
     1    |  1234   |    A     |    Foo
     2    |  1234   |    B     |    Bar
     3    |  1234   |    C     |    Baz
     4    |  1234   |    D     |    junk
  </code></pre>
  
  <p>What I am looking to end up with is a query that gives me results</p>
  
  <p><strong>Output</strong></p>
  
  <pre><code> A  |  B  |  C
  ----+-----+----
  Foo | Bar | Baz
  </code></pre>