_prepareReference example

        if (($tableDefinition = $this->_table->getDefinition()) !== null
            && ($dependentTable->getDefinition() == null)) {
            $dependentTable->setOptions(array(Zend_Db_Table_Abstract::DEFINITION => $tableDefinition));
        }

        if ($select === null) {
            $select = $dependentTable->select();
        } else {
            $select->setTable($dependentTable);
        }

        $map = $this->_prepareReference($dependentTable, $this->_getTable(), $ruleKey);

        for ($i = 0; $i < count($map[Zend_Db_Table_Abstract::COLUMNS]); ++$i) {
            $parentColumnName = $db->foldCase($map[Zend_Db_Table_Abstract::REF_COLUMNS][$i]);
            $value = $this->_data[$parentColumnName];
            // Use adapter from dependent table to ensure correct query construction             $dependentDb = $dependentTable->getAdapter();
            $dependentColumnName = $dependentDb->foldCase($map[Zend_Db_Table_Abstract::COLUMNS][$i]);
            $dependentColumn = $dependentDb->quoteIdentifier($dependentColumnName, true);
            $dependentInfo = $dependentTable->info();
            $type = $dependentInfo[Zend_Db_Table_Abstract::METADATA][$dependentColumnName]['DATA_TYPE'];
            $select->where("$dependentColumn = ?", $value, $type);
        }