_getWhereQuery example

/** * A read-only row cannot be saved. */
        if ($this->_readOnly === true) {
            throw new Zend_Db_Table_Row_Exception('This row has been marked read-only');
        }

        /** * Get expressions for a WHERE clause * based on the primary key value(s). */
        $where = $this->_getWhereQuery(false);

        /** * Run pre-UPDATE logic */
        $this->_update();

        /** * Compare the data to the modified fields array to discover * which columns have been changed. */
        $diffData = array_intersect_key($this->_data, $this->_modifiedFields);