doctrine / orm

        $baseTableAlias     = $this->getSQLTableAlias($this->class->name);

        // INNER JOIN parent tables

        foreach ($this->class->parentClasses as $parentClassName) {

            $conditions     = [];

            $tableAlias     = $this->getSQLTableAlias($parentClassName);

            $parentClass    = $this->em->getClassMetadata($parentClassName);

            $joinSql       .= ' INNER JOIN ' . $this->quoteStrategy->getTableName($parentClass, $this->platform) . ' ' . $tableAlias . ' ON ';

            foreach ($identifierColumns as $idColumn) {

                $conditions[] = $baseTableAlias . '.' . $idColumn . ' = ' . $tableAlias . '.' . $idColumn;

            }

            $joinSql .= implode(' AND ', $conditions);

        }

        return parent::getLockTablesSql($lockMode) . $joinSql;

    }

        $identifierColumn = $this->class->getIdentifierColumnNames();

        // INNER JOIN parent tables

        foreach ($this->class->parentClasses as $parentClassName) {

            $conditions   = [];

            $parentClass  = $this->em->getClassMetadata($parentClassName);

            $tableAlias   = $this->getSQLTableAlias($parentClassName);

            $joinSql     .= ' INNER JOIN ' . $this->quoteStrategy->getTableName($parentClass, $this->platform) . ' ' . $tableAlias . ' ON ';

            foreach ($identifierColumn as $idColumn) {

                $conditions[] = $baseTableAlias . '.' . $idColumn . ' = ' . $tableAlias . '.' . $idColumn;

            }

            $joinSql .= implode(' AND ', $conditions);

        }

        // OUTER JOIN sub tables

        foreach ($this->class->subClasses as $subClassName) {

        }

        // OUTER JOIN sub tables

        foreach ($this->class->subClasses as $subClassName) {

            $conditions  = [];

            $subClass    = $this->em->getClassMetadata($subClassName);

            $tableAlias  = $this->getSQLTableAlias($subClassName);

            $joinSql    .= ' LEFT JOIN ' . $this->quoteStrategy->getTableName($subClass, $this->platform) . ' ' . $tableAlias . ' ON ';

            foreach ($identifierColumn as $idColumn) {

                $conditions[] = $baseTableAlias . '.' . $idColumn . ' = ' . $tableAlias . '.' . $idColumn;

            }

            $joinSql .= implode(' AND ', $conditions);

        }

        return $joinSql;

    }