title: OpenSQL syntax CASE statement in WHERE condition
body: <p>I would like to ask if it is possible to write CASE statement directly into WHERE clause (I know that WHERE clause can be passed also by string) e.g.&nbsp;</p>
  
  <pre><code> SELECT * FROM db_table INTO TABLE @mt_table[]
       WHERE key1 = @l_key1
            AND key2 = @l_key2
            AND key3 = @l_key3
            AND key4 = @l_key4
            AND ( WHEN l_auth = 'A' THEN username = @sy-uname
                  WHEN l_auth = 'U' THEN username = @sy-uname OR username = @space 
                  END ). 
  </code></pre>