wocommunity/wonder — pull request #476 by hprange (2013-09-11 19:46:25+00:00)
Title: Add support to count distinct rows based on multiple columns using MySQL

This pull request complements the pull request #474 and #475 adding support to count distinct with multiple columns using MySQL. Even though this solution wasn't verified using a real system, the produced SQL expression is valid based on the MySQL documentation. I'm not going to merge this change unless someone confirms it really works on a real system.