Piwik\DataAccess\LogQueryBuilder\JoinGenerator::getJoinString PHP Method

    public function getJoinString()
    {
        return $this->joinString;
    }

 public function getSelectQueryString(SegmentExpression $segmentExpression, $select, $from, $where, $bind, $groupBy, $orderBy, $limitAndOffset)
 {
     if (!is_array($from)) {
         $from = array($from);
     }
     $fromInitially = $from;
     if (!$segmentExpression->isEmpty()) {
         $segmentExpression->parseSubExpressionsIntoSqlExpressions($from);
         $segmentSql = $segmentExpression->getSql();
         $where = $this->getWhereMatchBoth($where, $segmentSql['where']);
         $bind = array_merge($bind, $segmentSql['bind']);
     }
     $tables = new JoinTables($this->logTableProvider, $from);
     $join = new JoinGenerator($tables);
     $join->generate();
     $from = $join->getJoinString();
     $joinWithSubSelect = $join->shouldJoinWithSelect();
     // hack for https://github.com/piwik/piwik/issues/9194#issuecomment-164321612
     $useSpecialConversionGroupBy = !empty($segmentSql) && strpos($groupBy, 'log_conversion.idgoal') !== false && $fromInitially == array('log_conversion') && strpos($from, 'log_link_visit_action') !== false;
     if ($useSpecialConversionGroupBy) {
         $innerGroupBy = "CONCAT(log_conversion.idvisit, '_' , log_conversion.idgoal, '_', log_conversion.buster)";
         $sql = $this->buildWrappedSelectQuery($select, $from, $where, $groupBy, $orderBy, $limitAndOffset, $innerGroupBy);
     } elseif ($joinWithSubSelect) {
         $sql = $this->buildWrappedSelectQuery($select, $from, $where, $groupBy, $orderBy, $limitAndOffset);
     } else {
         $sql = $this->buildSelectQuery($select, $from, $where, $groupBy, $orderBy, $limitAndOffset);
     }
     return array('sql' => $sql, 'bind' => $bind);
 }